tst_QSpinBox::editingFinished() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: Ib08791375e3984e7eda5b25ec6bac0b283ed80cc
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/widgets/qspinbox/tst_qspinbox.cpp

@@ -927,7 +927,6 @@ void tst_QSpinBox::editingFinished()
     layout->addWidget(box2);
 
     testFocusWidget.show();
-    QApplicationPrivate::setActiveWindow(&testFocusWidget);
     QVERIFY(QTest::qWaitForWindowActive(&testFocusWidget));
     box->activateWindow();
     box->setFocus();