- documents what this method is about in the code (only in documentation so far)
- adds a missing test on the cli `swh db version` to check this behaves appropriately
- will allow to clean up duplicated code in existing backends (storage, indexer)  
- will allow to fix the backends which are missing the appropriate methods (scrubber,scheduler
scheduler, vaultscrubber, see 's descriptionvault, see 's description for details...)
Related to T4228
Depends on D7943 (revert of )
This is the proper fix instead of .