allow for scheduled Registry garbage collection

Summary

Provide a way to setup scheduled gargabe collection for the Docker Registry, at least with a helper just as possible with the Omnibus installation (see below), but preferably automated, without manual intervention required.

Current behavior

• as the gitlab-ctl command is not available for CNG, there is not straightforward way for Registry gargabe collection.
• manual gargabe collection is possible, but might lead to data corruption as there is not direct way to put the registry into r/o mode.

Expected behavior

• automated, scheduled gargabe collection using a Kubernetes-native approach (i.e. CronJob ressources)
• configurable just as possible for backups

Versions

• Chart: 5542c0ac