Cleans up /proc/find_safe_turf(), documenting and improving code (#93848)

## About The Pull Request

`/proc/find_safe_turf()` was cleaned up so that it did not have two
arguments that accomplished the same thing, removing opportunities for
user errors when calling the proc. Additionally, since I was here, I
decided to clean up some of the code and document it.

Some thresholds were changed in this PR (the max temperature threshold
was dropped from 360K to 340K), but I believe that it's better to keep
them consistent instead of using arbitrary values.

## Uncomfortably large gap

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## Changelog

No user facing changes.

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---------

Co-authored-by: Ghom <42542238+Ghommie@users.noreply.github.com>

code/modules/admin/fun_balloon.dm

@@ -135,11 +135,11 @@
 	var/effect_range = 5
 
 /obj/effect/fun_balloon/scatter/effect()
-	for(var/mob/living/M in range(effect_range, get_turf(src)))
-		var/turf/T = find_safe_turf(zlevel = src.z)
-		new /obj/effect/temp_visual/gravpush(get_turf(M))
-		M.forceMove(T)
-		to_chat(M, span_notice("Pop!"), confidential = TRUE)
+	for(var/mob/living/dispersed_mob in range(effect_range, get_turf(src)))
+		var/turf/drop_off = find_safe_turf(z)
+		new /obj/effect/temp_visual/gravpush(get_turf(dispersed_mob))
+		dispersed_mob.forceMove(drop_off)
+		dispersed_mob.balloon_alert(dispersed_mob, "pop!")
 
 // ----------- Station Crash
 // Can't think of anywhere better to put it right now