Removed code, wrongly removing the NavigationView's header

Author: szv

src/Codebreaker.Uno/CodebreakerUno/Views/Pages/ShellPage.xaml.cs

@@ -28,8 +28,5 @@ private void NavigationViewControl_DisplayModeChanged(NavigationView sender, Nav
             Right = AppTitleBar.Margin.Right,
             Bottom = AppTitleBar.Margin.Bottom
         };
-
-        if (sender.DisplayMode != NavigationViewDisplayMode.Expanded)
-            NavigationViewControl.Header = null;
     }
 }