End 1:1 call when partner leaves the call

### Your use case

#### What would you like to do?
1:1 calls should end when the other partner leaves.

#### Why would you like to do it?
This would match the behavior of a conventional call.

#### How would you like to achieve it?
This should be easy logic for anyone who knows their way around the code base.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you willing to provide a PR?

No