deploy fabric-tasks on install and keep up to date in puppet

all hosts should have a copy of fabric-tasks. there's many useful things in that repo, and we should keep expanding it to have more useful things.

it would skip a step in the install procedure, but it would also allow us to dump ad-hoc scripts that we currently leave lying around in /root or elsewhere.

this is part of the automated install task (#31239).

next steps:

• deploy fabric-tasks globally (or not?) currently done on profile::postgresql hosts and the fabric env
• deploy fabric (the debian package) (and fab command) globally (or not?)
• deploy fabric-tasks dependencies globally (or not?) will do if we need to, probably best with a debian package
• move python scripts from puppet-control to fabric (or not?) (see #41484 (comment 3156010)) not necessary
• cleanup old fabric-tasks/ (or tsa-misc/) incarnations (likely in /root)
• deploy fabric-tasks in the right place on install (done in ganeti, fabric pending on fabric-tasks!19 (merged))