Removes old duplicate backpack of holding singularity_act (#6130)

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## About The Pull Request
Funny enough, it was being overridden by the correct one

https://github.com/Citadel-Station-13/Citadel-Station-13-RP/blob/a5ada8e75e396738fb53a1cad39e7d5122f49f79/code/game/objects/items/storage/backpack.dm#L64-L70

code/modules/power/singularity/act.dm

@@ -96,11 +96,6 @@
 /obj/effect/projectile/emitter/singularity_pull()
 	return
 
-/obj/item/storage/backpack/holding/singularity_act(S, current_size)
-	var/dist = max((current_size - 2), 1)
-	explosion(src.loc,(dist),(dist*2),(dist*4))
-	return 1000
-
 /turf/singularity_act(S, current_size)
 	ScrapeAway()
 	return 2