Doing this in an attempt to be kind to our Borg hosts in cases where the
prometheus-borg-textcollector.timer is restarted on all hosts and avoids
having all machines querying the Borg hosts within the same minute. Only
downside is that the timers will trigger every 75-ish minutes instead of
exactly every hour, but this should not be a problem.

Add a new role called prometheus_exporters which should be run on every
machine we have and starts different collectors depending on what group
the machine is in. Currently supported our the gitlab runner exporter,
rebuilder textcollector, mysqld-exporter, borg textcollector and an
node/arch exporter. The arch exporter monitors the security status and
pacman out of date packages gauge.