Fixes improper static list declarations + adds grep for it (#87207)

## About The Pull Request

I randomly came across a `var/list/static` in the code, which does not
actually do what was intended, and thought it was silly. A ctrl+f
revealed that this was a fairly common mistake, so I went and fixed all
the instances of it I could find.

~~Including one in lighting code, which it looked like they were trying
to create a global list to cache generated lighting sheet values for
speed, but it was just a normal list that got created each time
pointlessly. Now those values are actually being cached (using a global
var, because a `static` list was not the right thing to use there in the
first place).~~

Nevermind, it seems that this was in fact being cached even if it
shouldn't have been, because byond. Just rearranged it there seeing as
it works either way.


## Why It's Good For The Game

Code that does what it's supposed to

## Changelog

🆑
fix: fixes a bunch of improper static list declarations
/🆑

code/modules/mapping/ruins.dm

@@ -31,7 +31,7 @@
 		testing("Ruin \"[name]\" placed at ([central_turf.x], [central_turf.y], [central_turf.z])")
 
 		if(clear_below)
-			var/list/static/clear_below_typecache = typecacheof(list(
+			var/static/list/clear_below_typecache = typecacheof(list(
 				/obj/structure/spawner,
 				/mob/living/simple_animal,
 				/obj/structure/flora