tst_QItemDelegate::task257859_finalizeEdit() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I163589828d64e837b9c170e724bc44251e4f64ef
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/itemviews/qitemdelegate/tst_qitemdelegate.cpp

@@ -1338,7 +1338,6 @@ void tst_QItemDelegate::task257859_finalizeEdit()
     QListView view;
     view.setModel(&model);
     view.show();
-    QApplicationPrivate::setActiveWindow(&view);
     view.setFocus();
     QVERIFY(QTest::qWaitForWindowActive(&view));