Mark ui_data procs as SHOULD_NOT_SLEEP(TRUE) (#17847)

* mark ui_data procs as SHOULD_NOT_SLEEP(TRUE)

* Address dm warnings

code/modules/tgui/external.dm

@@ -29,6 +29,11 @@
  * * mob/user - The mob interacting with the UI.
  */
 /datum/proc/ui_data(mob/user)
+	// Two good reasons why it shouldn't:
+	// 1) this is polled several times a second, so sleeping means more running threads, needlessly tanking performance
+	// 2) if you try to sleep, you get fun bugs ranging from BSOD to uninteractable white windows, to windows straight up vanishing.
+	// Just don't.
+	SHOULD_NOT_SLEEP(TRUE)
 	return list() // Not implemented.
 
 /**
@@ -43,6 +48,7 @@
  * * mob/user - The mob interacting with the UI.
  */
 /datum/proc/ui_static_data(mob/user)
+	SHOULD_NOT_SLEEP(TRUE)
 	return list()
 
 /**