Cleanup and simplitfy the async state update (#9390)

* Cleanup and simplitfy the async state update

* Update test_entity.py

homeassistant/components/alarm_control_panel/mqtt.py

@@ -87,7 +87,7 @@ class MqttAlarm(alarm.AlarmControlPanel):
                 _LOGGER.warning("Received unexpected payload: %s", payload)
                 return
             self._state = payload
-            self.hass.async_add_job(self.async_update_ha_state())
+            self.async_schedule_update_ha_state()
 
         return mqtt.async_subscribe(
             self.hass, self._state_topic, message_received, self._qos)