Revert "SSmachines instancing PR (#9080)"

This reverts commit 4889b33cea.

code/modules/power/antimatter/shielding.dm

@@ -147,7 +147,7 @@
 
 /obj/machinery/am_shielding/proc/setup_core()
 	processing = 1
-	begin_processing()
+	START_MACHINE_PROCESSING(src)
 	if(!control_unit)	return
 	control_unit.linked_cores.Add(src)
 	control_unit.reported_core_efficiency += efficiency
@@ -199,4 +199,4 @@
 		qdel(src)
 		return
 	..()
-	return
+	return

code/modules/power/powernet.dm

@@ -21,7 +21,7 @@
 	var/problem = 0				// If this is not 0 there is some sort of issue in the powernet. Monitors will display warnings.
 
 /datum/powernet/New()
-	START_PROCESSING_MACHINERY(src, SSMACHINES_POWERNETS_LIST)
+	START_PROCESSING_POWERNET(src)
 	..()
 
 /datum/powernet/Destroy()
@@ -31,7 +31,7 @@
 	for(var/obj/machinery/power/M in nodes)
 		nodes -= M
 		M.powernet = null
-	STOP_PROCESSING_MACHINERY(src, SSMACHINES_POWERNETS_LIST)
+	STOP_PROCESSING_POWERNET(src)
 	return ..()
 
 //Returns the amount of excess power (before refunding to SMESs) from last tick.