Lag War 2: Revengeance (#21950)

<img width="750" height="449" alt="image"
src="https://github.com/user-attachments/assets/29c06609-eb62-42be-9b9c-334f9fe88636"
/>

Ports: tgstation/tgstation#75769, tgstation/tgstation#72572,
tgstation/tgstation#93054

Fixes the holodeck causing 800 trillion hard dels that brings the server
to its knees. Stops turrets, weather system, and overmap contacts from
generating 500+ timers every tick by just using vars instead.

---------

Signed-off-by: Wildkins <john.wildkins@gmail.com>

code/modules/holodeck/HolodeckControl.dm

@@ -315,6 +315,8 @@ GLOBAL_LIST_EMPTY_TYPED(holodeck_controls, /obj/machinery/computer/holodeck_cont
 	active = 1
 	update_use_power(POWER_USE_ACTIVE)
 
+	QDEL_LIST(holodeck_landmarks)
+
 	for(var/item in holographic_objs)
 		derez(item)