tst_QGraphicsProxyWidget::clickFocus() remove setActiveWindow()

2f6fe3a268 has made calls to
QApplicationPrivate::setActiveWindow() redundant.

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: Icf9c4b1378eb244edb56f900ba74469abc38314f
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/graphicsview/qgraphicsproxywidget/tst_qgraphicsproxywidget.cpp

@@ -3342,7 +3342,6 @@ void tst_QGraphicsProxyWidget::clickFocus()
         view.setFrameStyle(0);
         view.resize(300, 300);
         view.show();
-        QApplicationPrivate::setActiveWindow(&view);
         QVERIFY(QTest::qWaitForWindowActive(&view));
 
         QVERIFY(!proxy->hasFocus());