Mob Destroy Refactoring (#22573)

Refactoring the entire destroy proc path from Mob Human all the way down
to Atom while trying to find the causes for the damn mob human hard
deletes. This PR comprehensively reorganizes every single stray
snowflake var used by /atom/ all the way to /mob/living/carbon/human,
and makes sure that every var that COULD store a reference, is now
cleared during the entirety of the Mob Destroy() parent hierarchy.

This may very well be the end of the lag war. 

In total, I've hunted down and cleared 39 hanging references between
/atom and /mob/living/carbon/human

---------

Signed-off-by: VMSolidus <evilexecutive@gmail.com>

code/modules/client/client_color.dm

@@ -4,11 +4,6 @@
 	var/override = FALSE //If set to override we will stop multiplying the moment we get here. NOTE: Priority remains, if your override is on position 4, the other 3 will still have a say.
 	var/disability = FALSE
 
-/mob
-	var/list/client_colors = list()
-
-
-
 /*
 	Adds an instance of color_type to the mob's client_colors list
 	color_type - a typepath (subtyped from /datum/client_color)

code/modules/client/preference_setup/origin/origin.dm

@@ -1,7 +1,3 @@
-/mob/living/carbon/human
-	var/singleton/origin_item/culture/culture
-	var/singleton/origin_item/origin/origin
-
 /datum/category_item/player_setup_item/origin
 	name = "Origin"
 	sort_order = 1