Backup and streaming snapshots may fill up the disk

[josef podany]

Describe the bug

Snapshot files are filling up Regatta disk space if for whatever reason is a snapshot not deleted after its use it will remain there indefinitely.

To Reproduce

Keep regatta running for some time and check for non cleaned snapshots.

Expected behavior

Snapshot do not fill up the disk space and do not cause disk pressure on the node.

Environment

The bug does not depend on an environment.

Additional context

• Snapshots should not be placed in ephemeral storage but rather on a mounted volume.
• Snapshots should be periodically cleaned.

Relates to #44.