tst_QMenuBar::check_altClosePress() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I7c949c9d279aea52ee774db65d9cf0033ac60fef
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/widgets/qmenubar/tst_qmenubar.cpp

@@ -907,7 +907,6 @@ void tst_QMenuBar::check_altClosePress()
 
     w.show();
     w.move(QGuiApplication::primaryScreen()->availableGeometry().center());
-    QApplicationPrivate::setActiveWindow(&w);
     QVERIFY(QTest::qWaitForWindowActive(&w));
 
     QTest::keyClick(&w, Qt::Key_F, Qt::AltModifier);