Revert "Handle large chain calc better (#17291)" (#17334)

This reverts commit bdf82ef  (#17291)

This seems to have stopped persisting auth chains for new events, and so
is causing state res to fall back to the slow methods

synapse/storage/controllers/persist_events.py

@@ -617,25 +617,13 @@ async def _persist_event_batch(
                         room_id, chunk
                     )
 
-            with Measure(self._clock, "calculate_chain_cover_index_for_events"):
-                # We now calculate chain ID/sequence numbers for any state events we're
-                # persisting. We ignore out of band memberships as we're not in the room
-                # and won't have their auth chain (we'll fix it up later if we join the
-                # room).
-                #
-                # See: docs/auth_chain_difference_algorithm.md
-                new_event_links = await self.persist_events_store.calculate_chain_cover_index_for_events(
-                    room_id, [e for e, _ in chunk]
-                )
-
             await self.persist_events_store._persist_events_and_state_updates(
                 room_id,
                 chunk,
                 state_delta_for_room=state_delta_for_room,
                 new_forward_extremities=new_forward_extremities,
                 use_negative_stream_ordering=backfilled,
                 inhibit_local_membership_updates=backfilled,
-                new_event_links=new_event_links,
             )
 
         return replaced_events