Cleanup mirrors with invalid routes
From @DouweM comment in https://gitlab.com/gitlab-com/infrastructure/issues/3118#note_45260621:
- We should clean these projects up.
17 have validation error
["Route path has already been taken", "Route is invalid"]
- All 17 have a route with validation error
["Path has already been taken"]
These are duplicated projects that should be cleaned up.