The $() was being interpolated by the caller, and the
pg_upgradecluster command was incomplete.

The list of packages to upgrade is undigestible. An example:

    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    Calculating upgrade... Done
    The following packages were automatically installed and are no longer required:
      dh-python emacs24-nox g++-6 gnupg-agent libann0 libbind9-140 libcryptsetup4 libdns162 libevent-2.0-5 libevtlog0 libgdbm3 libgmime-2.6-0 libicu57 libisc160
      libisccc140 libisccfg140 liblvm2app2.2 liblvm2cmd2.02 liblwres141 libncursesw5 libnotmuch4 libonig4 libperl5.24 libprocps6 libpython3.5 libpython3.5-minimal
      libpython3.5-stdlib libruby2.3 libssl1.0.2 libstdc++-6-dev libtalloc2 libunbound2 libunistring0 libustr-1.0-1 libxapian30 libyajl2 python3-distutils
      python3-lib2to3 python3.5 python3.5-minimal ruby-nokogiri ruby-pkg-config ruby-rgen ruby-safe-yaml ruby2.3
    Use 'sudo apt autoremove' to remove them.
    The following packages will be REMOVED:
      emacs24-bin-common emacs24-common libcurl3 libllvm3.8 syslog-ng-mod-json
    The following NEW packages will be installed:
      binutils-common binutils-x86-64-linux-gnu cpp-8 dirmngr emacs-bin-common emacs-common emacs-nox fdisk fonts-noto-core fonts-noto-ui-core g++-8 gcc-7-base gcc-8
      gcc-8-base gnupg-l10n gnupg-utils gpg gpg-agent gpg-wks-client gpg-wks-server gpgconf gpgsm install-info libaio1 libargon2-1 libasan5 libb-hooks-op-check-perl
      libbind9-161 libbinutils libboost-atomic1.67.0 libboost-chrono1.67.0 libboost-date-time1.67.0 libboost-filesystem1.67.0 libboost-locale1.67.0 libboost-log1.67.0
      libboost-program-options1.67.0 libboost-regex1.67.0 libboost-system1.67.0 libboost-thread1.67.0 libbrotli1 libcom-err2 libcpp-hocon0.1.7
      libcrypt-openssl-random-perl libcryptsetup12 libcurl4 libdevel-callchecker-perl libdns1104 libdynaloader-functions-perl libefiboot1 libefivar1 libev4 libext2fs2
      libfacter3.11.0 libfl2 libfribidi0 libgcc-8-dev libgdbm-compat4 libgdbm6 libgumbo1 libhtml-gumbo-perl libicu63 libirs161 libisc1100 libisccc161 libisccfg163
      libisl19 libjansson4 liblab-gamut1 liblcms2-2 libleatherman1.4.2 libllvm7 liblmdb0 liblvm2cmd2.03 liblwres161 libmpfr6 libncurses6 libncursesw6 libnftnl11 libonig5
      libpcre2-8-0 libperl5.28 libprocps7 libpython2-stdlib libpython3.7 libpython3.7-minimal libpython3.7-stdlib libruby2.5 libsnappy1v5 libstdc++-8-dev
      libsub-quote-perl libtinfo6 libubsan1 libuchardet0 libunwind8 libutf8proc2 libyaml-cpp0.6 linux-image-4.19.0-9-amd64 perl-modules-5.28 postgresql-11
      postgresql-client-11 python-pyasn1 python-pyasn1-modules python-scandir python2 python2-minimal python3-dbus python3-distro-info python3-distutils python3-lib2to3
      python3.7 python3.7-minimal ruby-xmlrpc ruby2.5 runit-helper
    The following packages will be upgraded:
      acl acpid adduser amavisd-new apache2 apache2-bin apache2-data apache2-utils apt-show-versions arj at augeas-lenses bacula-common bacula-fd base-files base-passwd
      bash bash-completion bind9-host binutils bsd-mailx bsdmainutils bsdutils build-essential bzip2 ca-certificates cabextract ccze clamav clamav-base clamav-daemon
      clamav-freshclam coreutils cpio cpp cron curl dash dbconfig-common dbus dctrl-tools debconf debconf-i18n debconf-utils debian-archive-keyring debianutils deborphan
      debsums dh-python dialog diffstat diffutils distro-info-data dmeventd dmsetup dns-root-data dnsutils dpkg-dev dstat e2fslibs e2fsprogs ed elinks elinks-data
      emacs24-nox emacsen-common etckeeper facter fail2ban file findutils finger fontconfig fontconfig-config fonts-liberation fonts-noto-hinted ftp g++ gawk gcc
      gettext-base git git-man gnupg gnupg-agent gnupg2 gnutls-bin gpgv graphviz grep groff-base grub-common grub-pc grub-pc-bin grub2-common gzip hostname htop ifupdown
      init init-system-helpers initramfs-tools initramfs-tools-core initscripts insserv installation-birthday iproute2 iptables iputils-ping iputils-tracepath ipython
      irqbalance jq klibc-utils kmod ldap-utils ldapvi less lftp libacl1 libann0 libapache-logformat-compiler-perl libapache-session-perl libapache2-mod-perl2
      libapache2-reload-perl libapparmor1 libapr1 libaprutil1 libaprutil1-dbd-sqlite3 libaprutil1-ldap libapt-inst2.0 libapt-pkg-perl libarchive-zip-perl libasound2
      libasound2-data libassuan0 libatomic1 libattr1 libaudit-common libaudit1 libaugeas0 libb-hooks-endofscope-perl libberkeleydb-perl libblkid1 libbsd-resource-perl
      libbsd0 libbson-1.0-0 libbusiness-hours-perl libbytes-random-secure-perl libbz2-1.0 libcairo2 libcap-ng0 libcap2 libcap2-bin libcc1-0 libcdt5
      libcgi-emulate-psgi-perl libcgi-pm-perl libcgraph6 libcilkrts5 libclamav9 libclass-accessor-perl libclass-c3-perl libclass-c3-xs-perl libclass-container-perl
      libclass-data-inheritable-perl libclass-inspector-perl libclass-mix-perl libclone-perl libcomerr2 libcompress-raw-zlib-perl libconvert-uulib-perl
      libcookie-baker-perl libcpanel-json-xs-perl libcrypt-eksblowfish-perl libcrypt-openssl-bignum-perl libcrypt-openssl-rsa-perl libcrypt-ssleay-perl
      libcss-minifier-xs-perl libcss-squish-perl libcurl3-gnutls libdata-guid-perl libdata-page-perl libdata-perl-perl libdate-manip-perl libdatetime-format-natural-perl
      libdatetime-format-w3cdtf-perl libdatetime-locale-perl libdatetime-perl libdatetime-timezone-perl libdatrie1 libdb5.3 libdbd-pg-perl libdbi-perl libdbi1
      libdbus-1-3 libdebconfclient0 libdevel-stacktrace-perl libdevel-symdump-perl libdevmapper-event1.02.1 libdevmapper1.02.1 libdigest-hmac-perl libdpkg-perl libedit2
      libelf1 libemail-address-list-perl libemail-address-perl libencode-perl liberror-perl libexception-class-perl libexpat1 libexporter-tiny-perl libfcgi-perl
      libfcgi-procmanager-perl libfdisk1 libffi6 libfile-fnmatch-perl libfile-sharedir-perl libfile-which-perl libfilesys-notify-simple-perl libfont-freetype-perl
      libfontconfig1 libfreetype6 libfreezethaw-perl libfstrm0 libfuse2 libgc1c2 libgcc1 libgcrypt20 libgd-graph-perl libgd-perl libgd3 libgeoip1 libglib2.0-0
      libgmime-2.6-0 libgmp10 libgnupg-interface-perl libgomp1 libgpg-error0 libgpgme11 libgpm2 libgraphite2-3 libgssapi-krb5-2 libgvc6 libgvpr2 libharfbuzz0b
      libhtml-mason-perl libhtml-mason-psgihandler-perl libhtml-parser-perl libhtml-quoted-perl libhtml-rewriteattributes-perl libhtml-scrubber-perl libhtml-tree-perl
      libhttp-cookies-perl libhttp-entity-parser-perl libhttp-headers-fast-perl libhttp-message-perl libhttp-multipartparser-perl libhttp-negotiate-perl libidn11
      libio-pty-perl libio-socket-ssl-perl libio-stringy-perl libip4tc0 libip6tc0 libipc-run-perl libipc-sharelite-perl libiptc0 libitm1 libivykis0
      libjavascript-minifier-xs-perl libjpeg62-turbo libjq1 libjson-c3 libjson-maybexs-perl libjson-perl libk5crypto3 libkeyutils1 libklibc libkmod2 libkrb5-3
      libkrb5support0 libldap-2.4-2 libldap-common liblist-moreutils-perl liblist-utilsby-perl liblocale-gettext-perl liblocale-maketext-fuzzy-perl liblockfile-bin
      liblockfile1 liblog-any-perl liblog-dispatch-perl liblsan0 libltdl7 liblwp-protocol-https-perl liblz4-1 liblzma5 liblzo2-2 libmagic-mgc libmagic1 libmail-dkim-perl
      libmath-random-isaac-perl libmime-tools-perl libmime-types-perl libmodule-runtime-perl libmodule-scandeps-perl libmodule-versions-report-perl libmongoc-1.0-0
      libmoo-perl libmoox-handlesvia-perl libmoox-late-perl libmount1 libmpc3 libmpdec2 libmpx2 libmro-compat-perl libmspack0 libncurses5 libncursesw5 libnet-cidr-perl
      libnet-dns-perl libnet-http-perl libnet-ip-perl libnet-libidn-perl libnet-server-perl libnet-ssleay-perl libnet1 libnetaddr-ip-perl libnetfilter-acct1
      libnetfilter-conntrack3 libnetfilter-log1 libnfnetlink0 libnghttp2-14 libnpth0 libnuma1 libopts25 libossp-uuid-perl libossp-uuid16 libpackage-stash-perl
      libpam-modules libpam-modules-bin libpam-pwdfile libpam-runtime libpam-systemd libpam0g libpango-1.0-0 libpangocairo-1.0-0 libpangoft2-1.0-0
      libparams-classify-perl libparams-util-perl libparams-validate-perl libparams-validationcompiler-perl libparse-recdescent-perl libparse-syslog-perl libpathplan4
      libpcap0.8 libpcre3 libpcrecpp0v5 libperlio-eol-perl libpipeline1 libpixman-1-0 libplack-perl libpng16-16 libpopt0 libpq5 libproc-processtable-perl libprotobuf-c1
      libpsl5 libpython-stdlib libpython2.7-minimal libpython2.7-stdlib libpython3-stdlib libquadmath0 libreadline5 libreadline7 libregexp-common-net-cidr-perl
      libregexp-common-perl libregexp-ipv6-perl librole-tiny-perl librtmp1 libsasl2-2 libsasl2-modules-db libscalar-list-utils-perl libscope-upper-perl libseccomp2
      libselinux1 libsemanage-common libsemanage1 libsepol1 libserf-1-1 libsigsegv2 libslang2 libsm6 libsmartcols1 libsocket6-perl libsort-naturally-perl libspecio-perl
      libsqlite3-0 libss2 libssh2-1 libssl1.1 libstdc++6 libstrictures-perl libstring-shellquote-perl libsub-exporter-perl libsub-identify-perl libsub-name-perl
      libsub-uplevel-perl libsvn1 libsystemd0 libtalloc2 libterm-readkey-perl libterm-readline-gnu-perl libtest-tcp-perl libtext-charwidth-perl libtext-iconv-perl
      libtext-password-pronounceable-perl libtext-quoted-perl libtext-template-perl libthai-data libthai0 libtiff5 libtime-parsedate-perl libtimedate-perl libtinfo5
      libtokyocabinet9 libtree-simple-perl libtry-tiny-perl libtsan0 libtype-tiny-perl libubsan0 libudev1 libuniversal-require-perl libunix-syslog-perl liburi-perl
      libuuid1 libvariable-magic-perl libwant-perl libwebp6 libwrap0 libwww-form-urlencoded-perl libwww-perl libwww-robotrules-perl libx11-6 libx11-data libxapian30
      libxau6 libxcb-render0 libxcb-shm0 libxcb1 libxdot4 libxml-namespacesupport-perl libxml-parser-perl libxml-rss-perl libxml-sax-base-perl libxml-sax-expat-perl
      libxml-sax-perl libxml-simple-perl libxml-twig-perl libxml-xpath-perl libxml-xpathengine-perl libxml2 libxmu6 libxslt1.1 libxt6 libxtables12 libyajl2 libyaml-0-2
      libyaml-perl libyaml-syck-perl linux-base linux-image-amd64 linux-libc-dev lnav login logrotate logtail lsb-release lsof lvm2 make man-db mc mc-data mime-support
      molly-guard monitoring-plugins-basic monitoring-plugins-common moreutils mount mtr-tiny multiarch-support mutt nagios-nrpe-server nano ncdu ncurses-base
      ncurses-bin ncurses-term ndisc6 needrestart net-tools netbase netcat-openbsd nload ntp openssh-client openssh-server openssh-sftp-server openssl p7zip passwd patch
      pax perl perl-base perl-doc pinentry-curses postfix postfix-cdb postfix-pcre postfix-sqlite postgresql postgresql-client postgresql-client-common postgresql-common
      postgrey procmail procps prometheus-apache-exporter prometheus-node-exporter psmisc puppet pv python python-apt-common python-backports-shutil-get-terminal-size
      python-decorator python-enum34 python-gdbm python-ipython python-ipython-genutils python-ldap python-minimal python-pathlib2 python-pexpect python-pickleshare
      python-pkg-resources python-prompt-toolkit python-psycopg2 python-ptyprocess python-pygments python-simplegeneric python-six python-traitlets python-wcwidth
      python-yaml python2.7 python2.7-minimal python3 python3-apt python3-minimal pyzor qemu-guest-agent rake rcs re2c readline-common request-tracker4 rsync rt4-apache2
      rt4-clients rt4-db-postgresql ruby ruby-augeas ruby-did-you-mean ruby-filesystem ruby-json ruby-minitest ruby-nokogiri ruby-pkg-config ruby-power-assert ruby-rgen
      ruby-safe-yaml ruby-shadow ruby-test-unit rubygems-integration screen sed sensible-utils socat spamassassin spamc spampd ssh startpar strace subversion sudo swaks
      syslog-ng syslog-ng-core syslog-ng-mod-journal syslog-ng-mod-mongodb syslog-ng-mod-sql systemd systemd-sysv sysv-rc sysvinit-utils tar tcpdump tcsh telnet tmux
      tzdata ucf udev ulogd2 unattended-upgrades unbound unbound-anchor unbound-host unrar unrar-free unzip util-linux uuid-runtime vim vim-common vim-runtime
      vim-scripts w3m wget whois xfsprogs xxd xz-utils zlib1g zsh zsh-common
    640 upgraded, 114 newly installed, 5 to remove and 0 not upgraded.
    Need to get 0 B/360 MB of archives.
    After this operation, 746 MB of additional disk space will be used.
    Do you want to continue? [Y/n]

Does anyone really go through this and say "oooh, libyajl2 is being
upgraded, THAT IS NOT RIGHT!". No.

So just go.

The "Before it all starts" section wasn't very clear in its purpose
and scope, merge it with the "File layout" section.

It seems like the `htools:iextags:FOO` parameter is a PREFIX. So the
previous system didn't actually work, because (e.g.) no web-fsn:* tag
existed.

I have fixed the actual cluster to use service:* tags.

See team#29816

The rationale here is that Ganeti has its own inventory and capacity
evaluation system, so we do not *need* the Spreadsheet for that
purpose. We still do need the spreadsheet for cost tracking however,
so keep the documentation procedure for machines that "are not in
Ganeti", basically.