tst_QCompleter::QTBUG_14292_filesystem() remove setActiveWindow()

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

Remove redundant calls.

Task-number: QTBUG-121488
Change-Id: I6546dc09a51037d7c3dea5c816273ddfe3a8797e
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

tests/auto/widgets/util/qcompleter/tst_qcompleter.cpp

@@ -1662,7 +1662,6 @@ void tst_QCompleter::QTBUG_14292_filesystem()
 
     edit.move(200, 200);
     edit.show();
-    QApplicationPrivate::setActiveWindow(&edit);
     QVERIFY(QTest::qWaitForWindowActive(&edit));
     QCOMPARE(QApplication::activeWindow(), &edit);
     edit.setFocus();