[MIRROR] Fixes a bunch of harddels that are sourced from player action (#6252)

* Fixes a bunch of harddels that are sourced from player action

* Mirror!

Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>
Co-authored-by: Funce <funce.973@gmail.com>

code/game/objects/structures/displaycase.dm

@@ -399,8 +399,6 @@
 	var/sale_price = 20
 	///The Account which will receive payment for purchases. Set by the first ID to swipe the tray.
 	var/datum/bank_account/payments_acc = null
-	///We're using the same trick as paper does in order to cache the image, and only load the UI when messed with.
-	var/list/viewing_ui = list()
 
 /obj/structure/displaycase/forsale/update_icon_state()
 	icon_state = "[initial(icon_state)][broken ? "_broken" : (open ? "_open" : (!showpiece ? "_empty" : null))]"
@@ -416,7 +414,6 @@
 	if(!ui)
 		ui = new(user, src, "Vendatray", name)
 		ui.set_autoupdate(FALSE)
-		viewing_ui[user] = ui
 		ui.open()
 
 /obj/structure/displaycase/forsale/ui_data(mob/user)