test: Ignore timedatex.service disconnection messages

`timedatex.service` shuts down on inactivity. The overview page has a
proxy on the systemd service object to watch for property changes, which
will trigger a NoReply error on the proxy occasionally.

Adding this to dbus_error_matches_unknown() would hide actually
interesting errors when a service crashes in the middle; so let's not do
that, and ignore that message instead.

Author: martinpitt

test/common/testlib.py

@@ -1712,6 +1712,9 @@ def login_and_go(self, path: Optional[str] = None, user: Optional[str] = None, h
         "pcp-archive: no such metric: .*: Unknown metric name",
         "pcp-archive: instance name lookup failed:.*",
         "pcp-archive: couldn't create pcp archive context for.*",
+
+        # timedatex.service shuts down after timeout, runs into race condition with property watching
+        ".*org.freedesktop.timedate1: couldn't get all properties.*Error:org.freedesktop.DBus.Error.NoReply.*",
     ]
 
     default_allowed_messages += os.environ.get("TEST_ALLOW_JOURNAL_MESSAGES", "").split(",")