Call Django's setUpClass()/tearDownClass()

This lets Django do its thing without us having to implement it
ourselves:

- The durability stuff
- Checking the `databases` attribute (not used yet)

It does some other stuff that relies on attributes that we don't set so
ends up a noop.

Author: bluetech

pytest_django/fixtures.py

@@ -159,12 +159,8 @@ class PytestDjangoTestCase(test_case_class):  # type: ignore[misc,valid-type]
         if transactional and _reset_sequences:
             reset_sequences = True
 
-    if not transactional:
-        django.db.transaction.Atomic._ensure_durability = False
-
-        def reset_durability() -> None:
-            django.db.transaction.Atomic._ensure_durability = True
-        request.addfinalizer(reset_durability)
+    PytestDjangoTestCase.setUpClass()
+    request.addfinalizer(PytestDjangoTestCase.tearDownClass)
 
     test_case = PytestDjangoTestCase(methodName="__init__")
     test_case._pre_setup()