logind: ignore PropertiesChanged signals for jobs

Otherwise we get a (harmless) message like:
systemd-logind[30845]: Failed to process message [type=signal sender=:1.36 path=/org/freedesktop/systemd1/job/4674 interface=org.freedesktop.DBus.Properties member=PropertiesChanged signature=sa{sv}as]: Invalid argument

src/login/logind-dbus.c

@@ -2047,7 +2047,8 @@ int match_properties_changed(sd_bus *bus, sd_bus_message *message, void *userdat
 
         r = unit_name_from_dbus_path(path, &unit);
         if (r < 0)
-                return r;
+                /* quietly ignore non-units paths */
+                return r == -EINVAL ? 0 : r;
 
         session = hashmap_get(m->session_units, unit);
         if (session)