LobbyBrowserScreen: Permanent network issues will produce lots of stacking popups "unexpected network error"

[CrsiX]

Platform
Desktop, but probably also on Android

Describe the bug
In LobbyBrowser, there's the refreshing mechanism. If network fails longer, it will stack error popups. That's bad.

To Reproduce
Steps to reproduce the behavior:

1. Start game with network connectivity
2. Stop network connectivity
3. Every n seconds a new popup appears, stacking above each other

Expected behavior
Don't stack, show only a single info. Then silently ignore the others.