[autotests] Hopefully stabilise TestShellClient

Summary:
Apparently this test is flaky, based on the output I recieved we had
processed the un-fullscreen but not the un-maximise.

It seems possible the wayland thread could process when there's only one
request in the queue.

Test Plan:
Couldn't reproduce the original issue, it's a blind patch but the
current tests still pass.

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D16955

autotests/integration/shell_client_test.cpp

@@ -730,7 +730,10 @@ void TestShellClient::testMaximizedToFullscreen()
     QVERIFY(fullscreenChangedSpy.wait());
     if (decoMode == ServerSideDecoration::Mode::Server) {
          QVERIFY(sizeChangeRequestedSpy.wait());
-         // don't check count, XDG might legitimately get two updates
+         // XDG will legitimately get two updates. They might be batched
+         if (xdgShellSurface && sizeChangeRequestedSpy.count() == 1) {
+             QVERIFY(sizeChangeRequestedSpy.wait());
+         }
 
          // fails as we don't correctly call setMaximize(false)
          // but realistically the only toolkits that support the deco also use XDGShell