Exclude historical unread count from main events unread count

### Steps to reproduce

1. Join a room (seeing this with IRC and Matrix rooms)
2. Wait until there are unread messages and app badge counter is "1"
3. Leave room without catching up on the messages

### What happened?

Badge counter is there forever until you re-join the room and clear it. Even app restart does not clear it

### What did you expect?

I actually like that it remembers where I was if I leave and rejoin, but I would expect badge/notification to not show for rooms I am not **_currently_** in.

Edit: View [author's view](https://github.com/vector-im/element-web/issues/18437#issuecomment-894490442) about a potential resolution of this ticket

### Operating system

MacOS

### Application version

Version 1.7.34 (1.7.34)

### How did you install the app?

official download site a while ago