Feature request: allow a queue to be not removing from other queues when it starts

[p0358]

Right now when a queue starts up, it removes all players from all other queues. In principle it makes sense, but it'd be nice to make it configurable.

Use case: for example someone having a 5v5 "target" queue in a channel and a 3v3 "warmup" queue to start it earlier. We wouldn't want people in "warmup" queue removed from there once it starts up, as they mostly play it to eventually abandon it and eventually join the other one.