Fix room upgrades creating an empty room when auth fails (#12696)

Signed-off-by: Sean Quah <seanq@element.io>

tests/replication/test_sharded_event_persister.py

@@ -14,7 +14,6 @@
 import logging
 from unittest.mock import patch
 
-from synapse.api.room_versions import RoomVersion
 from synapse.rest import admin
 from synapse.rest.client import login, room, sync
 from synapse.storage.util.id_generators import MultiWriterIdGenerator
@@ -64,21 +63,10 @@ class EventPersisterShardTestCase(BaseMultiWorkerStreamTestCase):
 
         # We control the room ID generation by patching out the
         # `_generate_room_id` method
-        async def generate_room(
-            creator_id: str, is_public: bool, room_version: RoomVersion
-        ):
-            await self.store.store_room(
-                room_id=room_id,
-                room_creator_user_id=creator_id,
-                is_public=is_public,
-                room_version=room_version,
-            )
-            return room_id
-
         with patch(
             "synapse.handlers.room.RoomCreationHandler._generate_room_id"
         ) as mock:
-            mock.side_effect = generate_room
+            mock.side_effect = lambda: room_id
             self.helper.create_room_as(user_id, tok=tok)
 
     def test_basic(self):