Adds ghost role eligibility to various ghost roles. (#11549)

* Added ghost role eligibility to CTF, possession, random animal

* Also added possessed blade to it.

* Also removed some extraneous dead/observer things.

* ahaha whoops

code/modules/mob/living/simple_animal/hostile/mining_mobs/elites/elite.dm

@@ -161,7 +161,7 @@ While using this makes the system rely on OnFire, it still gives options for tim
 				INVOKE_ASYNC(src, .proc/arena_checks)
 			if(TUMOR_INACTIVE)
 				activity = TUMOR_ACTIVE
-				var/mob/dead/observer/elitemind = null
+				var/mob/elitemind = null
 				visible_message("<span class='boldwarning'>[src] begins to convulse.  Your instincts tell you to step back.</span>")
 				activator = user
 				if(!boosted)