Revert "Finishes the allocation refactor (#55965)" (#56137)

This reverts commit 87234f3fd8.

code/controllers/subsystem/processing/fields.dm

@@ -2,5 +2,5 @@ PROCESSING_SUBSYSTEM_DEF(fields)
 	name = "Fields"
 	wait = 2
 	priority = FIRE_PRIORITY_FIELDS
-	flags = SS_KEEP_TIMING | SS_NO_INIT | SS_BACKGROUND
+	flags = SS_KEEP_TIMING | SS_NO_INIT
 	runlevels = RUNLEVEL_GAME | RUNLEVEL_POSTGAME

code/controllers/subsystem/processing/processing.dm

@@ -3,7 +3,7 @@
 SUBSYSTEM_DEF(processing)
 	name = "Processing"
 	priority = FIRE_PRIORITY_PROCESS
-	flags = SS_POST_FIRE_TIMING|SS_NO_INIT
+	flags = SS_BACKGROUND|SS_POST_FIRE_TIMING|SS_NO_INIT
 	wait = 1 SECONDS
 
 	var/stat_tag = "P" //Used for logging

code/controllers/subsystem/processing/wet_floors.dm

@@ -3,6 +3,5 @@ PROCESSING_SUBSYSTEM_DEF(wet_floors)
 	priority = FIRE_PRIORITY_WET_FLOORS
 	wait = 10
 	stat_tag = "WFP" //Used for logging
-	flags = SS_BACKGROUND
 	var/temperature_coeff = 2
 	var/time_ratio = 1.5 SECONDS