tst_QAbstractItemView::QTBUG31411_noSelection() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: If1e4810a899431d78fd0d5c620497ecfe813c07e
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/itemviews/qabstractitemview/tst_qabstractitemview.cpp

@@ -1853,7 +1853,6 @@ void tst_QAbstractItemView::QTBUG31411_noSelection()
     moveCursorAway(&window);
 
     window.show();
-    QApplicationPrivate::setActiveWindow(&window);
     QVERIFY(QTest::qWaitForWindowActive(&window));
 
     qRegisterMetaType<QItemSelection>();