Transistion between 'talking' and 'hover' state on call tiles is disconcerting

### Steps to reproduce

1. Wait until someone is talking in your call. A green highlight will appear around their call tile.
2. Mouse over their call tile.
3. The highlight changes immediately to half sized, then slowly (~1s) changes to white.

### Outcome

#### What did you expect?

#### What happened instead?

This transition is a bit odd to look at. Here's a video (you can't see my mouse, but I'm putting it on and off of the call tile):

https://github.com/vector-im/element-call/assets/1342360/06194a82-a428-4019-b1e3-cb778ba8fe31

This feels a bit weird to interact with. I think it could be improved by having the thickness of the outline be the same in both the 'talking' and 'hover' state.

Alternatively, you could try speeding up the transition from green to white.

### Operating system

NixOS Linux

### Browser information

Chromium v117.0.5938.88

### URL for webapp

call.element.io

### Will you send logs?

No