tst_QGraphicsView::hoverLeave() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I0d16654ed837009391967b187f8dbe5dced0849d
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/graphicsview/qgraphicsview/tst_qgraphicsview.cpp

@@ -4884,7 +4884,6 @@ void tst_QGraphicsView::hoverLeave()
     scene.addItem(item);
 
     view.showNormal();
-    QApplicationPrivate::setActiveWindow(&view);
     QVERIFY(QTest::qWaitForWindowExposed(&view));
 
     QWindow *viewWindow = view.window()->windowHandle();