Disable gunner rat spawning until their bugs have been worked out

They’re frequently appearing behind walls, trees, or rocks, making them impossible to actually kill but still able to damage players. It’s especially bad in areas with a lot of overlapping terrain (such as “Into the Nest” or early parts of “Convocation of Decay”) where they’ll shoot through wooden structures unhindered and all you can do is try to speedrun past thema and hope there isn’t a swarm attacking.