Improve Resilience of CNPG backups

[crutonjohn]

Right now, backups are sent using barman to an S3 bucket running locally inside the cluster, which is then sucked up into the volsync system and backed up that way.

realistically we could probably skip the middle man and just go straight to B2, or send to s3-garage locally. there could be some cost implications if we ever need to restore from B2 but that might be worth the squeeze to simplify things a bit and remove in-cluster minio.

can either:

• back up direct to B2
• back up to s3-garage
• explore using volumesnapshots + volsync for backups/restores

[crutonjohn]

pointed cnpg to b2 directly for now, still want to test out volumesnapshots at some point.

would be nice to somehow use the volumesnapshot method + volsync to back things up