We want to store verification details only for
replicables that qualify for verification,
e.g. for MR diffs only externally stored diffs
are verified.

So, instead of autosaving child records, we
check for the same filters used in `available_verifiables`
and save the child object.

This commit also introduces a scope
`with_files_stored_locally` to limit verifiables
to locally stored files only, since verification
has not yet been implemented for remote object
storage.

EE: true
Changed: changed