tst_QGraphicsScene::focusOnTouch() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I8a55f99ef5e1fbbc71dc360989a40fc7d21326fb
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/graphicsview/qgraphicsscene/tst_qgraphicsscene.cpp

@@ -4811,7 +4811,6 @@ void tst_QGraphicsScene::focusOnTouch()
     rect->setFlag(QGraphicsItem::ItemIsFocusable, true);
 
     view.show();
-    QApplicationPrivate::setActiveWindow(&view);
     QVERIFY(QTest::qWaitForWindowActive(&view));
 
     QVERIFY(!rect->hasFocus());