DolphinQt: Remove redundant window hints

Remove window hints clearing the flag Qt::WindowContextHelpButtonHint,
which is already off by default in Qt 6.

In Qt 5 this flag was set by default for QDialogs, and on Windows put a
? button in the corner of the title bar allowing users to activate Qt's
QWhatsThis help system for a given widget. Since we don't set that text
the ? button was useless and so we hid it manually.

Source/Core/DolphinQt/NetPlay/NetPlaySetupDialog.cpp

@@ -32,7 +32,6 @@ NetPlaySetupDialog::NetPlaySetupDialog(const GameListModel& game_list_model, QWi
     : QDialog(parent), m_game_list_model(game_list_model)
 {
   setWindowTitle(tr("NetPlay Setup"));
-  setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
 
   CreateMainLayout();