Join process does finish if room has been previously left

### Steps to reproduce

1. Leave room R
2. Open room R preview screen
3. Join room R

### Outcome

#### What did you expect?
The join process to finish normally.

#### What happened instead?

It appears that the `[MXSession onJoinedRoom:success:]` waits for the `kMXRoomInitialSyncNotification` to call back `[MXSession joinRoom:viaServers:withThirdPartySigned:success:failure:]`. In this case `[MXEventTimeline handleJoinedRoomSync:onComplete:]` is called during the next sync but instead of posting `kMXRoomInitialSyncNotification` a `kMXRoomDidFlushDataNotification` is posted and that's why the flow is broken.

### Your phone model

_No response_

### Operating system version

_No response_

### Application version

_No response_

### Homeserver

_No response_

### Will you send logs?

No

Start with MXSession onJoinedRoom:success: and joinRoom:viaServers:withThirdPartySigned:success:failure:, then trace MXEventTimeline handleJoinedRoomSync:onComplete: during the next sync. Compare handling of kMXRoomInitialSyncNotification with kMXRoomDidFlushDataNotification for a room that was previously left. Done means the join process finishes normally after leaving, previewing, and rejoining the room.

Written by the indexing model from the issue text.