Use separate module for pytest settings (#13895)

* Use separate module for test settings

* Further refine some pre-existing comments in settings

* Add CACHES to setting snapshot exceptions to accommodate changed load order

awx/api/serializers.py

@@ -2190,7 +2190,7 @@ class BulkHostCreateSerializer(serializers.Serializer):
         host_data = []
         for r in result:
             item = {k: getattr(r, k) for k in return_keys}
-            if not settings.IS_TESTING_MODE:
+            if settings.DATABASES and ('sqlite3' not in settings.DATABASES.get('default', {}).get('ENGINE')):
                 # sqlite acts different with bulk_create -- it doesn't return the id of the objects
                 # to get it, you have to do an additional query, which is not useful for our tests
                 item['url'] = reverse('api:host_detail', kwargs={'pk': r.id})