Replace or remove the antag critter drops

[Gerhazo]

From what I've been told, the reason for antag critters having drops was to incentivize players to kill them. 

As another reason for them being added (iirc I think myself adding them?), the antag critter events were added bringing in additional antagonistic forces without to my knowledge other parts of the game being adjusted to account for it, so the loot is there to reward the station for having to deal with the extra trouble that wasn't there before (as well as a way to bring unique toys into the station).