Some Mob Define Cleanup (#22536)

Just removing a few ancient 2008-era vars that were on every mob
globally, but were completely unused in the modern code. I thought about
removing the Mutations too, but since the Hulk mutation is actually used
by a tiny handful of things, I would probably have to do that in a
separate PR by turning the Hulk code into an Element instead.

code/modules/admin/verbs/randomverbs.dm

@@ -782,7 +782,7 @@ Traitors and the like can also be revived with the previous role mostly intact.
 	message_admins("[key_name_admin(usr)] has gibbed [key_name_admin(M)]", 1)
 
 	if(isobserver(M))
-		gibs(M.loc, M.viruses)
+		gibs(M.loc)
 		return
 
 	M.gib()