sw: disable test_tdf118540_preview_document_properties()

See the discussion at <https://gerrit.libreoffice.org/#/c/70840/> this
test is quite unstable at the moment, unfortunately.

Change-Id: I6cbfdd0d9c5af8a848f32ab209ae70bc7a10d4af
Reviewed-on: https://gerrit.libreoffice.org/73557Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

sw/qa/uitest/writer_tests5/tdf118540.py

@@ -21,6 +21,8 @@ def get_url_for_data_file(file_name):
 
 class tdf118540(UITestCase):
    def test_tdf118540_preview_document_properties(self):
+        # FIXME flaky test, usually passes, but breaks regularly.
+        return
         writer_doc = self.ui_test.load_file(get_url_for_data_file("tdf118540.docx"))
         document = self.ui_test.get_component()
         self.xUITest.executeCommand(".uno:PrintPreview")  #open print preview