Turn more unmanaged global vars into GLOB (#20446)

Turned a ton of unmanaged globals into managed globals.
Refactored some UT output.
Removed some unused things, including vars.
Added a test to ensure people don't keep adding new unmanaged vars.

code/modules/spell_system/spells/spell_code.dm

@@ -1,4 +1,4 @@
-var/list/spells = typesof(/spell) //needed for the badmin verb for now
+GLOBAL_LIST_INIT(spells, typesof(/spell))
 
 /spell
 	var/name = "Spell"