tst_QGraphicsWidget::verifyFocusPolicy() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I2e3a630036b313696f62bbd3183c0448624395e8
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/graphicsview/qgraphicswidget/tst_qgraphicswidget.cpp

@@ -1679,7 +1679,6 @@ void tst_QGraphicsWidget::verifyFocusChain()
         w1_2->setFocusPolicy(Qt::StrongFocus);
         scene.addItem(w1_2);
         window->show();
-        QApplicationPrivate::setActiveWindow(window.data());
         QVERIFY(QTest::qWaitForWindowActive(window.data()));
 
         lineEdit->setFocus();