Test failures when v12 rooms are the default

## Failing tests on v12

### `tests/csapi`

Most of these tests directly do something with PLs causing them to break. Some weird quirks with sync though need investigation.

```
--- FAIL: TestRoomDeleteAlias (8.40s)
--- FAIL: TestRoomDeleteAlias/Parallel (0.00s)
--- FAIL: TestRoomDeleteAlias/Parallel/Users_with_sufficient_power-level_can_delete_other's_aliases (0.70s)
--- FAIL: TestRoomDeleteAlias/Parallel/Regular_users_can_add_and_delete_aliases_when_m.room.aliases_is_restricted (0.88s)

--- FAIL: TestRoomMembers (8.35s)
--- FAIL: TestRoomMembers/Parallel (0.00s)
--- FAIL: TestRoomMembers/Parallel/Test_that_we_can_be_reinvited_to_a_room_we_created (0.52s)

--- FAIL: TestDemotingUsersViaUsersDefault (7.36s)

--- FAIL: TestPowerLevels (7.51s)
--- FAIL: TestPowerLevels/GET_/rooms/:room_id/state/m.room.power_levels_can_fetch_levels (0.01s)
--- FAIL: TestPowerLevels/PUT_/rooms/:room_id/state/m.room.power_levels_can_set_levels (0.02s)
--- FAIL: TestPowerLevels/PUT_power_levels_should_not_explode_if_the_old_power_levels_were_empty (0.01s)

--- FAIL: TestRoomCreationReportsEventsToMyself (12.77s)
--- FAIL: TestRoomCreationReportsEventsToMyself/parallel (0.00s)
--- FAIL: TestRoomCreationReportsEventsToMyself/parallel/Room_creation_reports_m.room.create_to_myself (0.12s)

--- FAIL: TestSync (20.19s)
--- FAIL: TestSync/parallel (2.87s)
--- FAIL: TestSync/parallel/sync_should_succeed_even_if_the_sync_token_points_to_a_redaction_of_an_unknown_event (10.18s)

--- FAIL: TestSyncTimelineGap (18.62s)
--- FAIL: TestSyncTimelineGap/incremental (5.12s)
--- FAIL: TestSyncTimelineGap/full (5.16s)
```

### `tests`

Basically any test that uses the complement federation server is likely to be affected by this.

```
--- FAIL: TestIsDirectFlagFederation (7.66s)
--- FAIL: TestEventAuth (7.88s)
--- FAIL: TestFederationRedactSendsWithoutEvent (10.49s)
--- FAIL: TestInboundFederationRejectsEventsWithRejectedAuthEvents (13.96s)
--- FAIL: TestGetMissingEventsGapFilling (13.77s)
--- FAIL: TestOutboundFederationIgnoresMissingEventWithBadJSONForRoomVersion6 (8.16s)
--- FAIL: TestOutboundFederationEventSizeGetMissingEvents (8.14s)
--- FAIL: TestJoinViaRoomIDAndServerName (8.97s)
--- FAIL: TestJoinFederatedRoomWithUnverifiableEvents (7.96s)
--- FAIL: TestJoinFederatedRoomWithUnverifiableEvents//send_join_response_missing_signatures_shouldn't_block_room_join (0.00s)
--- FAIL: TestJoinFederatedRoomWithUnverifiableEvents//send_join_response_with_bad_signatures_shouldn't_block_room_join (0.00s)
--- FAIL: TestJoinFederatedRoomWithUnverifiableEvents//send_join_response_with_unobtainable_keys_shouldn't_block_room_join (0.00s)
--- FAIL: TestJoinFederatedRoomWithUnverifiableEvents//send_join_response_with_state_with_unverifiable_auth_events_shouldn't_block_room_join (0.00s)
--- FAIL: TestOutboundFederationSend (7.61s)
--- FAIL: TestNetworkPartitionOrdering (7.85s)
--- FAIL: TestSyncOmitsStateChangeOnFilteredEvents (8.16s)
--- FAIL: TestUnrejectRejectedEvents (7.92s)
```

Start by running the failing tests listed under tests/csapi and tests, focusing on cases involving power levels, sync, room creation, and federation. Compare failures with v12 rooms as the default and trace the Complement federation server interactions. Done means the listed failures pass with v12 as the default room version.

Written by the indexing model from the issue text.