Fixed RBAC migration tests considering new signal handlers that are a bit too helpful during testing

We have some signal handlers now that perform work that do work
automatically that we want to explicitly test in our migration path, so
we have to undo some things in order to test the migration code.

awx/main/tests/functional/test_rbac_user.py

@@ -10,11 +10,16 @@ def test_user_admin(user_project, project, user):
     admin = user('admin', is_superuser = True)
     sa = Role.singleton('System Administrator')
 
+    # this should happen automatically with our signal
+    assert sa.members.filter(id=admin.id).exists() is True
+    sa.members.remove(admin)
+
     assert sa.members.filter(id=joe.id).exists() is False
     assert sa.members.filter(id=admin.id).exists() is False
 
     migrations = rbac.migrate_users(apps, None)
 
+    # The migration should add the admin back in
     assert sa.members.filter(id=joe.id).exists() is False
     assert sa.members.filter(id=admin.id).exists() is True
     assert len(migrations) == 1