tst_QGroupBox::propagateFocus() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I2bcad29de4bcbb90a1e891a2f39db966288abdb1
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/widgets/qgroupbox/tst_qgroupbox.cpp

@@ -462,7 +462,6 @@ void tst_QGroupBox::propagateFocus()
     QGroupBox box;
     QLineEdit lineEdit(&box);
     box.show();
-    QApplicationPrivate::setActiveWindow(&box);
     QVERIFY(QTest::qWaitForWindowActive(&box));
     box.setFocus();
     QTRY_COMPARE(qApp->focusWidget(), static_cast<QWidget*>(&lineEdit));