Client: Make tst_nooutput more robust

We had auto configure on, but also manually configured half of the
configure event by hand.

This patch changes it to all be manual

Change-Id: Id130d71585c0d8a94107702e470de201fe1a189c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

tests/auto/wayland/nooutput/tst_nooutput.cpp

@@ -37,7 +37,7 @@ public:
     NoOutputCompositor()
     {
         exec([this] { removeAll<Output>(); });
-        m_config.autoConfigure = true;
+        m_config.autoConfigure = false;
     }
 };
 
@@ -68,6 +68,7 @@ void tst_nooutput::noScreens()
 
     exec([=] {
         xdgToplevel()->sendConfigure({0, 0}, {}); // Let the window decide the size
+        xdgSurface()->sendConfigure(nextSerial());
     });
 
     QTRY_VERIFY(window.isExposed());