[meta] Make git fsck results on Geo secondary useful

As raised in gitlab-org/gitlab-ee#5564:

Once the fsck results are in the tracking database, what do we intend to do with them?

The snapshotting functionality can successfully copy a variety of corrupt repositories from the primary, but we don't have a good strategy for verifying that they're broken in exactly the same way as they are on the primary, at present.