audit last year's nagios notifications for proper coverage in Prometheus

compare nagios alerts with prometheus to make sure we are not missing anything (see also #41713 (closed) for another audit).

Those are the alerts that fired in the last year since this issue was filed, in decreasing number of occurences:

• apt - security updates (#41633 (closed), missing timestamp in #41355 (closed) and obsolete #41712 (closed))
• needrestart (#41633 (closed))
• uptime check (rejected in TPA-RFC-33)
• load (planned in phase B, #41639 (closed))
• disk usage (#41633 (closed))
• system - all services running (planned in phase B, #41639 (closed))
• network service, mostly covered by the blackbox exporter (#41632 (closed)), that is:
  • onionoo varnish (delegated in TPA-RFC-33, to confirm)
  • onionoo full service check (delegated in TPA-RFC-33, to confirm)
  • onionoo backend (delegated in TPA-RFC-33, to confirm)
  • nrpe (N/A, equivalent to JobDown check now, #41633 (closed))
  • https (#41632 (closed))
  • ntp peer (planned in phase B, #41639 (closed))
  • ntp time (planned in phase B, #41639 (closed))
  • https cert (#41632 (closed), #41633 (closed), also postponed to phase B in #41731 (closed))
  • http (#41632 (closed))
  • sshd (#41632 (closed))
  • smtp (#41632 (closed))
• PING (planned in phase B, #41639 (closed))
• puppet - catalog run (planned in phase B, #41639 (closed))
• is DOWN ** (#41633 (closed), #41632 (closed))
• RAID - DRBD (#41633 (closed))
• process (rejected in TPA-RFC-33)
• setup - ud-ldap freshness (planned in phase B, #41639 (closed))
• swap usage - percent (planned in phase B, #41639 (closed))
• backup (#41633 (closed))
• puppet - all catalog runs (planned in phase B, #41639 (closed))
• application service - bridgedb status (delegated in TPA-RFC-33, covered by anticensorship)
• DNS SOA sync (planned in phase B, #41639 (closed))
• unwanted (rejected in TPA-RFC-33)
• collector2 (delegated in TPA-RFC-33, to confirm)
• mirror static sync (planned in phase B, #41639 (closed))
• DNS (planned in phase B, #41794)
  • DNS SOA sync
  • DNS - DS expiry
  • DNS - delegation and signature expiry
  • DNS - security delegations
  • DNS - zones signed properly
• processes - total (rejected in TPA-RFC-33)
• Ganeti - cluster (planned in phase B, #41639 (closed))
• SSL cert - db.torproject.org (planned in phase B, #41732 (closed))
• collector (delegated in TPA-RFC-33, to confirm)
• Ganeti - instances (planned in phase B, #41639 (closed))
• system - filesystem check (planned in phase B, #41639 (closed))
• swap usage - mb (planned in phase B, #41639 (closed))
• unbound trust anchors (planned in phase B, #41639 (closed))
• mail queue (delegated in TPA-RFC-33, rejected by anticensorship)
• CPU - intel ucode (#41633 (closed))
• postgresql backups (#41633 (closed), #41774 (closed))
• onionoo - ping backend onionoo-backend-02 (delegated in TPA-RFC-33, to confirm)
• RAID - sw raid (#41633 (closed))
• processes - zombies (rejected in TPA-RFC-33)
• RAID - megaraid SAS (N/A, host retirement)
• network - v6 gw (rejected in TPA-RFC-33)
• users (rejected in TPA-RFC-33)
• SSL cert - host (postponed to phase B, #41732 (closed))
• redis liveness on crm-int-01 from crm-ext-01 (#41633 (closed))
• RAID - unexpected sw raid (rejected in TPA-RFC-33)
• bridges.tpo web service (delegated in TPA-RFC-33, covered by anticensorship)
• SSL certs - LE (#41633 (closed), also postponed to phase B in #41731 (closed))
• mirror sync (planned in phase B, #41639 (closed))
• onionoo - ping backend onionoo-backend-01 (delegated in TPA-RFC-33, to confirm)
• SAN health status (N/A, host retirement)
• translation cron - stuck (removed before retirement)
• icmp probe - RAID controller module 1 port 2 iSCSI interface (N/A, host retirement)
• icmp probe - RAID controller module 0 management interface (N/A, host retirement)