Exclude proxy from load balancer if it reaches max capacity #395
Description
When a proxy is full, we must exclude it from the load balancing, so Kubernetes does not redirect new players to this proxy.
Moreover, some load balancer providers (like GCP) needs a bit of a time to take into account load balancer inclusion and exclusion. So, for this feature to work perfectly, we must take into account some lag. The easiest way of doing this is to consider a proxy full when the capacity is almost reached (with a configurable delta). This will allow the load balancer to still send some players until it had the time to update itself.
The default delta will be 15 players. So, for a proxy with a capacity of 1000 players, it will be considered full when 985 players are connected.