Add E2E test of `TimelineCard` (with maximized widget / on video room)

### Your use case

#### What would you like to do?

Create E2E test of `TimelineCard` with a maximized widget, or on a video room.

#### Why would you like to do it?

It is crucial to ensure that everything on `TimelineCard` should exist inside the panel and not overflow, such as `MessageActionBar`, read receipts groups, timestamp, etc.

#### How would you like to achieve it?

### Have you considered any alternatives?

_No response_

### Additional context

The issue of read receipts group being rendered outside of TimelineCard / ThreadView happens and regresses frequently. See: https://github.com/vector-im/element-web/issues/21774