Fixes some synthetic language oversights (#76846)

## About The Pull Request

#76305 removed the knowledge of every language from silicons, but this
had a couple of oversights.
This language set was not only used by cyborgs but also bots and vending
machines.

A couple of effects relied on them knowing all of those languages,
specifically their emp_act and also the station trait which rerolled
their languages.
Now they actually _learn_ a random language and start speaking it
instead.

Also I fixed a related runtime which I noticed in testing where a bot
would die as a result of being EMPed, delete itself, and then try and do
a bunch more shit after it stopped existing. Annoying.

Why was I looking at bot languages? Haha don't worry about it 😇 

## Why It's Good For The Game

Restores function of a funny feature.

## Changelog

🆑
fix: Station traits can once again allow vending machines and bots to
speak a random language
fix: EMPed bots and vending machines once again speak a random language
/🆑

code/modules/client/preferences/language.dm

@@ -12,7 +12,7 @@
 /datum/preference/choiced/language/init_possible_values()
 	var/list/values = list()
 
-	if(!GLOB.roundstart_languages.len)
+	if(!GLOB.uncommon_roundstart_languages.len)
 		generate_selectable_species_and_languages()
 
 	values += "Random"
@@ -21,9 +21,7 @@
 	var/datum/language/uncommon/uncommon_language = /datum/language/uncommon
 	values += initial(uncommon_language.name)
 
-	for(var/datum/language/language_type as anything in GLOB.roundstart_languages)
-		if(ispath(language_type, /datum/language/common))
-			continue
+	for(var/datum/language/language_type as anything in GLOB.uncommon_roundstart_languages)
 		if(initial(language_type.name) in values)
 			continue
 		values += initial(language_type.name)