Fixes lua breaking when registering signals on turfs (#83018)

## About The Pull Request
Signals don't get removed on turfs when they're deleted. This fixes that
so that it is reflected in lua as well.

## Why It's Good For The Game
Lua bugfixes

## Changelog
🆑
fix: Fixed lua scripts breaking when turfs with registered signals get
deleted.
/🆑

---------

Co-authored-by: Watermelon914 <3052169-Watermelon914@users.noreply.gitlab.com>

lua/handler_group.lua

@@ -14,7 +14,7 @@ function HandlerGroup:register_signal(datum, signal, func)
 	if not callback then
 		return
 	end
-	table.insert(self.registered, { datum = datum, signal = signal, callback = callback  })
+	table.insert(self.registered, { datum = dm.global_proc("WEAKREF", datum), signal = signal, callback = callback  })
 end
 
 -- Clears all the signals that have been registered on this HandlerGroup