Makes necropolis stone tiles un-hittable (#96819)

## About The Pull Request

Removes ``CAN_BE_HIT`` from necropolis stone tiles, preventing them from
being attacked with items

## Why It's Good For The Game

They are completely indestructible and are meant to function as decals.
Them being hittable results in accidental attacks during fights near/in
ruins, which steals players' clicks and is generally very annoying to
deal with.

## Changelog
🆑
qol: Necropolis stone tiles can no longer be hit
/🆑

code/modules/mapfluff/ruins/objects_and_mobs/necropolis_gate.dm

@@ -255,6 +255,7 @@ GLOBAL_DATUM(necropolis_gate, /obj/structure/necropolis_gate/legion_gate)
 	layer = ABOVE_OPEN_TURF_LAYER
 	anchored = TRUE
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF
+	obj_flags = NONE
 	var/tile_key = "pristine_tile"
 	var/tile_random_sprite_max = 24