Element relies on own member event in sync

### Steps to reproduce

On a Conduit Matrix server:

1. Join a room
2. Let someone else send messages so none of your events are in the recent timeline anymore
3. Clear cache

### Outcome

#### What did you expect?

The room displays normally

#### What happened instead?

Room is in archived section

My theory is that Element expects the user's own member event to be in the initial sync, but Conduit omits it due to lazy loading.

### Operating system

-

### Browser information

-

### URL for webapp

app.element.io

### Application version

_No response_

### Homeserver

Conduit

### Will you send logs?

No