Follow-up to https://github.com/matrix-org/synapse/pull/12083

Since we are now using the new `state_event_ids` parameter to do all of the heavy lifting.
We can remove any spots where we plumbed `auth_event_ids` just for MSC2716 things in
https://github.com/matrix-org/synapse/pull/9247/files.

Removing `auth_event_ids` from following functions:

 - `create_and_send_nonmember_event`
 - `_local_membership_update`
 - `update_membership`
 - `update_membership_locked`