This change makes closes another migration! And remotes tests around it,
mostly due to stubbing this was needed. Also, these are tested on the
Gitaly side too:
- https://gitlab.com/gitlab-org/gitaly/issues/791
-
https://gitlab.com/gitlab-org/gitaly/blob/6dd74543f6af8ebcf22aa10e39da004f388fdda5/internal/service/repository/fetch_remote_test.go

Closes https://gitlab.com/gitlab-org/gitaly/issues/789