tst_QItemDelegate::enterKey remove QApplicationPrivate::setActiveWindow

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I13872112fe33457c8843eb6982d8231022a5083a
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

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

@@ -1279,7 +1279,6 @@ void tst_QItemDelegate::enterKey()
     QListView view;
     view.setModel(&model);
     view.show();
-    QApplicationPrivate::setActiveWindow(&view);
     view.setFocus();
     QVERIFY(QTest::qWaitForWindowActive(&view));