[TF2] Stop the GC from assigning players during the last 30 or 15 seconds of a Casual match

[gaelcoral]

One of the issues with Casual matchmaking is that sometimes autobalance kicks in during the final seconds of a match, moving players to the losing team just before it ends.

It also happens that the Game Coordinator assigns players to matches that are about to finish, placing them on the losing team with only a few seconds left.

This results in unfair MMR losses and negatively affects the balance of the Glicko skill rating system, which becomes less accurate over time due to these situations.

[kisak-valve]

Hello @gaelcoral, the autobalance half of this request is a duplicate of #2602. let's use this issue report to focus on the coordinator.

[programmedsun]

Game Coordinator cant do anything against a match thats close 2 finish, it assumes that the match is active until the game says otherwise.