Remove Shower Processing (#23134)

There's about ~5500 processing entries in the Machinery subsystem, at
any given point showers are about 50 of them. This PR just makes it so
that showers that aren't on automatically remove themselves from
processing to free up time for the machinery subsystem.

code/game/objects/structures/watercloset.dm

@@ -179,6 +179,7 @@
 	on = !on
 	update_icon()
 	if(on)
+		START_PROCESSING(SSmachinery, src)
 		if (M.loc == loc)
 			wash(M)
 			process_heat(M)
@@ -271,7 +272,7 @@
 
 /obj/structure/machinery/shower/process()
 	if(!on)
-		return
+		return PROCESS_KILL
 	wash_floor()
 	if(!mobpresent)
 		return

html/changelogs/hellfirejag-kill-shower-processing.yml

@@ -0,0 +1,4 @@
+author: Hellfirejag
+delete-after: True
+changes:
+  - bugfix: "Made showers no longer require always processing."