Fixes a signal override for Sound Tokens and potentially fixes a harddel when clients logged out while hearing sound tokens (#96472)

🆑
fix: Fixes a hard-del and signal override with sound tokens
/🆑


The comsig issue was basically: both source and listener register for
qdel, but they can be the same thing resulting in a double register.
lame!

the hard-del was caused by me running remove_listener when a client
logged out of a mob...but at that point the client is null...so we cant
clear its sound tokens. boo! not smart!

code/modules/client/client_procs.dm

@@ -632,6 +632,8 @@ GLOBAL_LIST_INIT(unrecommended_builds, list(
 
 	QDEL_LIST_ASSOC_VAL(char_render_holders)
 
+	sound_tokens = null
+
 	SSambience.remove_ambience_client(src)
 	SSmouse_entered.hovers -= src
 	SSping.currentrun -= src
@@ -643,6 +645,7 @@ GLOBAL_LIST_INIT(unrecommended_builds, list(
 	QDEL_NULL(loot_panel)
 	QDEL_NULL(parallax_rock)
 	seen_messages = null
+	sound_tokens = null
 	Master.UpdateTickRate()
 	..() //Even though we're going to be hard deleted there are still some things that want to know the destroy is happening
 	return QDEL_HINT_HARDDEL_NOW