One of the older sets of unit tests we had was the "policy" tests, which

checked the .accessible() methods on some managers and

.is_accessible_by() methods on some models. These covered Group,

Repository, and ReviewRequest models (and managers), but weren't

part of theor respective test suites.
This gets rid of the old policy test suite, modernizes/cleans up the

tests, and moves them into the proper test suites. This enhances test

coverage and prepares for some upcoming unit tests to refine behavior

and fix bugs.

Unit tests pass.