Revert #25303 and subsequent fixes (#25613)

* Revert "Be safe, radios. (#25595)"

This reverts commit bfa88abd5a.

* Revert "Fixes various radio issues (#25586)"

This reverts commit 9296564ab6.

* Revert "refactors radios to use proximity (#25303)"

This reverts commit 06db6bc004.

* One more bit that needed reverting.

* Begone, unnecessary file!

---------

Co-authored-by: FunnyMan3595 (Charlie Nolan) <funnyman@google.com>

code/modules/mob/dead/observer/observer_base.dm

@@ -952,11 +952,5 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 		log_debug("[key_name(src)] ended up in regular cleanup_observe rather than the mentor cleanup observe despite having TRAIT_MENTOR_OBSERVING. This is likely a bug and may result in them being stuck outside of their bodies.")
 	cleanup_observe()
 
-/mob/dead/observer/proc/update_dead_radio()
-	if(get_preference(PREFTOGGLE_CHAT_GHOSTRADIO))
-		GLOB.deadchat_radio.listeners |= src
-	else
-		GLOB.deadchat_radio.listeners -= src
-
 #undef GHOST_CAN_REENTER
 #undef GHOST_IS_OBSERVER

code/modules/mob/dead/observer/observer_login.dm

@@ -10,5 +10,3 @@
 	if(GLOB.non_respawnable_keys[ckey])
 		can_reenter_corpse = 0
 		REMOVE_TRAIT(src, TRAIT_RESPAWNABLE, GHOSTED)
-	
-	update_dead_radio()