Leverage Gitaly when deleting repositories

What does this MR do?

Gitaly and GitLab do many of the same things when removing a repository:

1. They move the repository for a while
2. Schedule deletion of the moved repository
3. 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.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content