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/WiiUpdate.cpp

@@ -96,7 +96,6 @@ static WiiUtils::UpdateResult ShowProgress(QWidget* parent, Callable function, A
   UpdateProgressDialog dialog{parent};
   dialog.setLabelText(QObject::tr("Preparing to update...\nThis can take a while."));
   dialog.setWindowTitle(QObject::tr("Updating"));
-  dialog.setWindowFlags(dialog.windowFlags() & ~Qt::WindowContextHelpButtonHint);
   // QProgressDialog doesn't set its minimum size correctly.
   dialog.setMinimumSize(360, 150);