AI mobs won't suicide every time they ventcrawl (#89328)

## About The Pull Request

Some kind of refactor to how AI behaviours work kind of messed this one
up, all of its return values that ended the proc and stopped the suicide
timer were relying on a return value... from a proc called in a timer
that could never possibly get sent as the return value for the relevant
proc.
I fixed it to just call `finish_behaviour` instead.

## Changelog

🆑
fix: AI-controlled ventcrawling mobs (botanical spiderlings and legioned
monkeys) can once more do so without killing themselves shortly
afterwards.
/🆑

code/datums/ai/basic_mobs/basic_ai_behaviors/ventcrawling.dm

@@ -82,7 +82,8 @@
 
 	if(!HAS_TRAIT(living_pawn, TRAIT_MOVE_VENTCRAWLING) && isturf(get_turf(living_pawn))) // we're out of the vents, so no need to do an exit
 		// assume that we got yeeted out somehow and return this so we can halt the suicide pill timer.
-		return AI_BEHAVIOR_DELAY | AI_BEHAVIOR_SUCCEEDED
+		finish_action(controller, TRUE, target_key)
+		return
 
 	living_pawn.forceMove(exit_vent)
 	if(!living_pawn.can_enter_vent(exit_vent, provide_feedback = FALSE))
@@ -90,7 +91,8 @@
 		emergency_vent = calculate_exit_vent(controller)
 		if(isnull(emergency_vent))
 			// it's joever. we cooked too hard.
-			return suicide_pill(controller) | AI_BEHAVIOR_DELAY
+			suicide_pill(controller)
+			return
 
 		controller.set_blackboard_key(BB_EXIT_VENT_TARGET, emergency_vent) // assign and go again
 		addtimer(CALLBACK(src, PROC_REF(exit_the_vents), controller), (rand(controller.blackboard[BB_LOWER_VENT_TIME_LIMIT], controller.blackboard[BB_UPPER_VENT_TIME_LIMIT]) / 2)) // we're in danger mode, so scurry out at half the time it would normally take.
@@ -99,9 +101,11 @@
 	living_pawn.handle_ventcrawl(exit_vent)
 	if(HAS_TRAIT(living_pawn, TRAIT_MOVE_VENTCRAWLING)) // how'd we fail? what the fuck
 		stack_trace("We failed to exit the vents, even though we should have been fine? This is very weird.")
-		return suicide_pill(controller) | AI_BEHAVIOR_DELAY // all of the prior checks say we should have definitely made it through, but we didn't. dammit.
+		suicide_pill(controller)
+		return
 
-	return AI_BEHAVIOR_DELAY | AI_BEHAVIOR_SUCCEEDED // we did it! we went into the vents and out of the vents. poggers.
+	finish_action(controller, TRUE, target_key)
+	return
 
 /// Incredibly stripped down version of the overarching `can_enter_vent` proc on `/mob, just meant for rapid rechecking of a vent. Will be TRUE if not blocked, FALSE otherwise.
 /datum/ai_behavior/crawl_through_vents/proc/is_vent_valid(obj/machinery/atmospherics/components/unary/vent_pump/checkable)