Fixed #23947 -- Django's test suite doesn't pass in reverse order

Fixed inconsistent tests when running Django's test suite with --reverse option.
I'd guess one or more of the tests aren't cleaning up after themselves properly and leaving some state that affects a subsequent test. Might take some time to figure out why. Could be helpful to break the single tests.py file into a couple files like `test_templatetags.py`, `test_commands.py`, `test_storages.py`, etc.