Remove training card window

This was a leftover from attempts at modifying MaSzyna for professional simulators.
Interaction with this window could cause a crash.

utilities/Globals.cpp

@@ -787,12 +787,6 @@ bool global_settings::ConfigParseUI(cParser& Parser, const std::string& token)
         return true;
     }
 
-    if (token == "gui.trainingdefault")
-    {
-        ParseOne(Parser, gui_trainingdefault, 1);
-        return true;
-    }
-
     return false;
 }