arch-audit hung as it was started before there was a working internet
connection. To work around this issue, add proper Wants/After targets
for network-online.target and for the rebuilderd textcollector let it
start after rebuilderd.service is "online".

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pacman out of date packages gauge.