tst_QComboBox::flaggedItems remove QApplicationPrivate::setActiveWindow

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I49a2b3809f76e6f9db8e807bc4dcdc9d11c43fcb
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/widgets/qcombobox/tst_qcombobox.cpp

@@ -2055,7 +2055,6 @@ void tst_QComboBox::flaggedItems()
     comboBox.setView(&listWidget);
     comboBox.move(200, 200);
     comboBox.show();
-    QApplicationPrivate::setActiveWindow(&comboBox);
     comboBox.activateWindow();
     comboBox.setFocus();
     QVERIFY(QTest::qWaitForWindowActive(&comboBox));