[EE] Rework push mirror retries
What does this MR do?
This is an EE port of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31247
It adds the "last attempt" column to the pull-mirror row
This is an EE port of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31247
It adds the "last attempt" column to the pull-mirror row