Multiplayer rooms can get stuck for 2 minutes after match has finished

[kiwec]

Here's how it goes:

1. One player fails to load in the map (either they're tabbed out, or some other issue happened)
2. After ~30 seconds of waiting, the map starts
3. At the end of the map, "Waiting for all players to finish..." is displayed
4. Everybody has to wait ~2 minutes for the match to "finish", and can't leave as the escape button does nothing.

Kicking the "afk" player ends the match instantly, but this is only applicable to bot-managed rooms. The leaderboard is hidden after you finish the map, so players don't know who is "afk" with 0 score.

Proposed fix: if the player has not loaded the map after 30 seconds, kick them from the match.