[autotests] Don't change screens during cleanup

Screens are set during init, to do so at cleanup doesn't bring a lot.

It leads to a potential awkward raciness with xwayland failing the test,
whilst doing something that isn't part of what we're testing here or
likely to happen in real life.

autotests/integration/internal_window.cpp

@@ -209,8 +209,6 @@ void InternalWindowTest::init()
 void InternalWindowTest::cleanup()
 {
     Test::destroyWaylandConnection();
-
-    QMetaObject::invokeMethod(kwinApp()->platform(), "setVirtualOutputs", Qt::DirectConnection, Q_ARG(int, 2));
 }
 
 void InternalWindowTest::testEnterLeave()