Fixes radio encryption key quantum entanglement (#95210)

## About The Pull Request

Radio encryption key removal handling, including nulling, is handled in
`Exited()`. The key never exits the radio if it wasn't inside the radio
to begin with.

## Why It's Good For The Game

fixes #95207

## Changelog
🆑

fix: Radio encryption keys are no longer tied to their radios once
removed

/🆑

code/game/objects/items/devices/radio/radio.dm

@@ -102,7 +102,7 @@
 	. = ..()
 
 	if(ispath(keyslot))
-		keyslot = new keyslot()
+		keyslot = new keyslot(src)
 		recalculateChannels()
 
 	perform_update_icon = FALSE