Fix For /turf/closed/mineral/asteroid (#5778)

## About The Pull Request

[The latest upstream
merge](https://github.com/Bubberstation/Bubberstation/pull/5733) added
new icons for red rocks and broke the overrides from the wall pr. I've
taken the liberty of simply killing the override as I think they look
far nicer than the icons I made.

## Why It's Good For The Game

No more trypophobia.

## Changelog

🆑 Robwo
del: removed redundant red rock/porous iron rock override icons
/🆑

modular_zubbers/code/modules/general_sprite_overrides/turfs/walls.dm

@@ -216,12 +216,6 @@
 
 
 // ROCK WALLS
-/turf/closed/mineral/asteroid
-	icon = MAP_SWITCH('modular_zubbers/icons/turf/walls/red_wall.dmi', 'icons/turf/mining.dmi')
-
-/turf/closed/mineral/random/stationside/asteroid
-	icon = MAP_SWITCH('modular_zubbers/icons/turf/walls/red_wall.dmi', 'icons/turf/mining.dmi')
-
 /turf/closed/indestructible/rock
 	icon = 'modular_zubbers/icons/turf/walls/smoothrocks.dmi'
 	icon_state = "smoothrocks-0"
@@ -239,7 +233,6 @@
 	canSmoothWith = SMOOTH_GROUP_CLOSED_TURFS
 	smoothing_flags = SMOOTH_BITMASK | SMOOTH_BORDER
 
-
 /turf/closed/indestructible/rock/snow/ice
 	icon = 'modular_zubbers/icons/turf/walls/icerock_wall.dmi'
 	icon_state = "icerock_wall-0"
@@ -261,9 +254,6 @@
 	smoothing_groups = SMOOTH_GROUP_WALLS + SMOOTH_GROUP_CLOSED_TURFS
 	canSmoothWith = SMOOTH_GROUP_AIRLOCK + SMOOTH_GROUP_WINDOW_FULLTILE + SMOOTH_GROUP_WALLS
 
-/turf/closed/wall/rock
-	icon = 'modular_zubbers/icons/turf/walls/reinforced_rock.dmi'
-
 
 // FALSE WALLS
 /obj/structure/falsewall