Update message preview in room list for calls

### Your use case

#### What would you like to do?
The room list shows message previews, if I receive a call in the room I get a notification but the message preview doesn't change.

#### Why would you like to do it?
When the message preview does not change it's confusing because I've already read that message and I don't know why I have an unread notification there now

#### How would you like to achieve it?
I suggest we have a stock message in the preview that says the thing that matches the tombstone text in the timeline --

This screenshot shows the last text-message in the room (which I've already read) and then an unread @ and a count because they just tried to call me -- but I don't know that from the message preview... feels weird

When I go to the timeline, it looks like this:

The message preview text should/could say "video call"

### Have you considered any alternatives?

_No response_

### Additional context

_No response_