Reduce Lists Memory usage, update CI (#17706)

* Convert alerts to a lazylist

* Convert fullscreens to lazylist

* Convert ckeys_allowed_itemspawn to a lazylist

* Convert camera lists to lazylists

* Get rid of an old unused footstep_sounds list

* Make flooring_cache a lazy list

* Fix flooring_blacklist, convert a bunch more flooring lists to lazylists

* Improve ci byond caching

code/game/objects/items.dm

@@ -114,7 +114,7 @@
 	var/climbing_delay = 1 //If rock_climbing, lower better.
 	var/digestable = TRUE
 	var/item_tf_spawn_allowed = FALSE
-	var/list/ckeys_allowed_itemspawn = list()
+	var/list/ckeys_allowed_itemspawn = null
 
 /obj/item/Initialize(mapload)
 	. = ..()

code/game/objects/items/devices/ai_detector.dm

@@ -49,16 +49,6 @@
 	if(!T)
 		return PROXIMITY_OFF_CAMERANET
 
-	// Security is also a concern, so we need to see if any cameras are in use.
-	// Note that this will trigger upon the security console being used, regardless if someone is actually watching,
-	// because there isn't a nice way to test if someone is actually looking.  Probably better that way too.
-	var/list/our_local_area = range(range_alert, T)
-	for(var/obj/machinery/camera/C in our_local_area)
-		if(C.camera_computers_using_this.len) // Only check cameras actively being used.
-			var/list/their_local_area = C.can_see(range_alert)
-			if(T in their_local_area)
-				return PROXIMITY_ON_SCREEN
-
 	// Now for the somewhat harder AI cameranet checks.
 
 	// Check if we are even on the cameranet.

code/game/objects/items/devices/communicator/communicator.dm

@@ -351,8 +351,8 @@ var/global/list/obj/item/communicator/all_communicators = list() //Don't change
 
 /obj/machinery/camera/communicator/Initialize(mapload)
 	. = ..()
-	client_huds |= GLOB.global_hud.whitense
-	client_huds |= GLOB.global_hud.darkMask
+	LAZYOR(client_huds, GLOB.global_hud.whitense)
+	LAZYOR(client_huds, GLOB.global_hud.darkMask)
 
 //It's the 26th century. We should have smart watches by now.
 /obj/item/communicator/watch