Butchering requires you to be in combat mode. (#69510)

This was an oversight that occurred when intents were replaced with combat mode

	if(user.a_intent != INTENT_HARM)
		return

was never replaced by its combat mode equivalent.
This is relevant today because it makes it impossible to preform surgeries on dead monkeys (you will just butcher them)

code/datums/components/butchering.dm

@@ -37,6 +37,8 @@
 /datum/component/butchering/proc/onItemAttack(obj/item/source, mob/living/M, mob/living/user)
 	SIGNAL_HANDLER
 
+	if(!user.combat_mode)
+		return
 	if(M.stat == DEAD && (M.butcher_results || M.guaranteed_butcher_results)) //can we butcher it?
 		if(butchering_enabled && (can_be_blunt || source.get_sharpness()))
 			INVOKE_ASYNC(src, .proc/startButcher, source, M, user)