Complete automation of backup testing

To finish automating the backup restore process there are only a few steps left. In an ideal world instead of having monthly backup appreciation day we could have a nightly cron job that automatically restores a recent backup and prometheus alerts notifying us if there hasn't been a known good backup recently.

Blockers for this are:

• Azure credentials would need to be delegated to the job
• The gpg key and the passphrase protecting it would need to be fetched from a chef vault (?) instead of 1password
• The restore target and any other parameters that are manually chosen now (e.g. the resource group) would need to be determined automatically