Some explosions code cleanup (#57493)

Clears out two deprecated explosions systems (explosion ids and explosion levels)
Refactors a bunch of contents_explosions procs to be maybe slightly faster.
Cleans up a bunch of ex_act code.
Slightly cleaner code
A few less unused vars on /atom and /turf

code/modules/mining/machine_redemption.dm

@@ -347,7 +347,7 @@
 
 /obj/machinery/mineral/ore_redemption/ex_act(severity, target)
 	do_sparks(5, TRUE, src)
-	..()
+	return ..()
 
 /obj/machinery/mineral/ore_redemption/update_icon_state()
 	icon_state = "[initial(icon_state)][powered() ? null : "-off"]"

code/modules/mining/machine_vending.dm

@@ -200,7 +200,7 @@
 
 /obj/machinery/mineral/equipment_vendor/ex_act(severity, target)
 	do_sparks(5, TRUE, src)
-	if(prob(50 / severity) && severity < 3)
+	if(prob(50 / severity) && severity < EXPLODE_LIGHT)
 		qdel(src)
 
 /****************Golem Point Vendor**************************/

code/modules/mining/ores_coins.dm

@@ -131,9 +131,8 @@ GLOBAL_LIST_INIT(sand_recipes, list(\
 	qdel(src)
 
 /obj/item/stack/ore/glass/ex_act(severity, target)
-	if (severity == EXPLODE_NONE)
-		return
-	qdel(src)
+	if(severity != EXPLODE_NONE)
+		qdel(src)
 
 /obj/item/stack/ore/glass/basalt
 	name = "volcanic ash"
@@ -335,9 +334,8 @@ GLOBAL_LIST_INIT(sand_recipes, list(\
 	pixel_y = base_pixel_y + rand(0, 8) - 8
 
 /obj/item/stack/ore/ex_act(severity, target)
-	if (!severity || severity >= 2)
-		return
-	qdel(src)
+	if(severity == EXPLODE_DEVASTATE)
+		qdel(src)
 
 
 /*****************************Coin********************************/