feat: Cleans up some of the shutdown logic so that the MQTTClient is disconnected properly.

Sources/dewPoint-controller/Application.swift

@@ -40,7 +40,7 @@ struct Application {
       $0.topicPublisher = .live(client: mqtt)
       $0.mqttConnectionManager = .live(client: mqtt, logger: logger)
     } operation: {
-      let mqttConnection = MQTTConnectionService(cleanSession: false, logger: logger)
+      let mqttConnection = MQTTConnectionService(logger: logger)
       let sensors = SensorsService(sensors: .live, logger: logger)
 
       var serviceGroupConfiguration = ServiceGroupConfiguration(