Updates shotgun ammo boxes in ships to the new version. (#2676)

## About The Pull Request
Updates shotgun ammo boxes in ships to the new version. Hyena,
Halftrack, Cepheus and Twinkleshine.

## Why It's Good For The Game
The new version is a lot better to use and this probably overdue.
## Changelog

:cl:
fix: updated ship shotgun ammo boxes
/:cl:

_maps/shuttles/independent/independent_halftrack.dmm

@@ -200,16 +200,16 @@
 /obj/machinery/airalarm/directional/south,
 /obj/machinery/firealarm/directional/west,
 /obj/structure/closet/crate/secure/weapon,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/beanbag,
-/obj/item/storage/box/beanbag,
-/obj/item/storage/box/beanbag,
-/obj/item/storage/box/beanbag,
-/obj/item/storage/box/beanbag,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g/beanbag,
+/obj/item/ammo_box/a12g/beanbag,
+/obj/item/ammo_box/a12g/beanbag,
+/obj/item/ammo_box/a12g/beanbag,
+/obj/item/ammo_box/a12g/beanbag,
 /obj/effect/turf_decal/box/red,
 /turf/open/floor/plasteel/dark,
 /area/ship/security)

_maps/shuttles/minutemen/minutemen_cepheus.dmm

@@ -4108,15 +4108,9 @@
 /obj/item/ammo_box/magazine/m45{
 	pixel_x = 6
 	},
-/obj/item/storage/box/rubbershot{
-	pixel_x = 3;
-	pixel_y = -3
-	},
+/obj/item/ammo_box/a12g/rubbershot,
 /obj/item/ammo_box/magazine/cm15_mag,
-/obj/item/storage/box/rubbershot{
-	pixel_x = 3;
-	pixel_y = -3
-	},
+/obj/item/ammo_box/a12g/rubbershot,
 /turf/open/floor/plasteel/tech/grid,
 /area/ship/security)
 "RN" = (

_maps/shuttles/syndicate/syndicate_gorlex_hyena.dmm

@@ -300,7 +300,7 @@
 /obj/effect/decal/cleanable/dirt/dust,
 /obj/machinery/airalarm/directional/north,
 /obj/effect/turf_decal/industrial/outline,
-/obj/item/storage/box/lethalshot,
+/obj/item/ammo_box/a12g,
 /obj/item/ammo_box/c10mm,
 /turf/open/floor/mineral/plastitanium,
 /area/ship/security/armory)

_maps/shuttles/syndicate/syndicate_twinkleshine.dmm

@@ -3719,9 +3719,9 @@
 /obj/item/ammo_casing/caseless/rocket,
 /obj/item/ammo_casing/caseless/rocket/hedp,
 /obj/item/ammo_casing/caseless/rocket/hedp,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
-/obj/item/storage/box/lethalshot,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
+/obj/item/ammo_box/a12g,
 /obj/item/gun/ballistic/rocketlauncher,
 /obj/item/gun/ballistic/automatic/ebr,
 /obj/item/gun/ballistic/automatic/ebr{