Fixes a decal hard del (#81093)

## About The Pull Request

Attempting to fix this hard del here: 


![firefox_1QHRZHx9GY](https://github.com/tgstation/tgstation/assets/13398309/871d50e4-1bfc-4b16-82af-972162e8d2e4)

I think the cause is from the turf changing, which
`/datum/elements/connect_loc` does not seem to take into consideration.
Now it should.

Also cleans up the signals in `/datum/component/infective/` which may be
another potential cause of issues.

## Why It's Good For The Game

Code that cleans up after itself is nice.

## Changelog

🆑
fix: fixes a hard del with decals
/🆑

code/datums/components/infective.dm

@@ -161,3 +161,20 @@
 /datum/component/infective/proc/try_infect(mob/living/L, target_zone)
 	for(var/V in diseases)
 		L.ContactContractDisease(V, target_zone)
+
+/datum/component/infective/UnregisterFromParent()
+	. = ..()
+	UnregisterSignal(parent, list(
+		COMSIG_FOOD_EATEN,
+		COMSIG_PILL_CONSUMED,
+		COMSIG_COMPONENT_CLEAN_ACT,
+		COMSIG_MOVABLE_BUMP,
+		COMSIG_MOVABLE_IMPACT_ZONE,
+		COMSIG_ITEM_ATTACK_ZONE,
+		COMSIG_ITEM_ATTACK,
+		COMSIG_ITEM_EQUIPPED,
+		COMSIG_GLASS_DRANK,
+		COMSIG_ORGAN_IMPLANTED,
+		COMSIG_GIBS_STREAK,
+	))
+	qdel(GetComponent(/datum/component/connect_loc_behalf))

code/datums/elements/connect_loc.dm

@@ -24,7 +24,7 @@
 
 /datum/element/connect_loc/proc/update_signals(atom/movable/listener)
 	var/atom/listener_loc = listener.loc
-	if(isnull(listener_loc))
+	if(QDELETED(listener) || QDELETED(listener_loc))
 		return
 
 	for (var/signal in connections)