Remove bogus C# finalizers (#28315)

Begging people to learn how this programming language works before throwing random syntax into a file.

None of these finalizers ever worked. I also checked whether they were memory leaks and needed *proper* shutdown logic, but they're all instantiated-once UI controls that last for the entire lifetime of the program so it's probably fine.

Content.Client/Interaction/DragDropHelper.cs

@@ -73,11 +73,6 @@ public sealed class DragDropHelper<T>
         _cfg.OnValueChanged(CCVars.DragDropDeadZone, SetDeadZone, true);
     }
 
-    ~DragDropHelper()
-    {
-        _cfg.UnsubValueChanged(CCVars.DragDropDeadZone, SetDeadZone);
-    }
-
     /// <summary>
     /// Tell the helper that the mouse button was pressed down on
     /// a target, thus a drag has the possibility to begin for this target.