tst_QItemDelefate::testLineEditValidate() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I212eedf0f6101b40c22c6afdeb2d434f0e762889
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

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

@@ -1469,7 +1469,6 @@ void tst_QItemDelegate::testLineEditValidation()
     view.setItemDelegate(&delegate);
     view.show();
     view.setFocus();
-    QApplicationPrivate::setActiveWindow(&view);
     QVERIFY(QTest::qWaitForWindowActive(&view));
 
     QPointer<QLineEdit> editor;