pluto: configure backups

[mweinelt]

• sets the mountpoints for prometheus and victoriametrics dataset
• copies the backup module from non-critical-infra
• prepare the backup to the storagebox
• configure backups to include prometheus, grafana, victoriametrics

[mweinelt]

Untested.

[mweinelt]

Deployed and tested. I think the zfs integration in the backup module provides sufficient decoupling for now.