Leverage Gitaly when deleting repositories
What does this MR do?
Gitaly and GitLab do many of the same things when removing a repository:
- They move the repository for a while
- Schedule deletion of the moved repository
- Have another check if the data is actually removed
This is not necessary, one could be removed. I feel like Gitaly is responsible to remove data it's been requested to remove, as such the logic in Rails can be removed.