Remove unused global mock methods

Created by: camdencheek

This PR removes a bunch of now-unused global mocks. It should be possible now to write all new tests with the new injected DB mocks, so there is no good reason to keep these around. Also, it makes it more clear how much work is left to remove the global mocks entirely.

Very mechanical change. The process is just:

1. Find references on the mock struct field
2. If the only reference is where the global mock is checked for nil-ness, remove it