Remove redundant MQTT subscribe

include/wlan.h

@@ -20,6 +20,8 @@ void connect_mqtt();
 
 void wlan_connection_handler(WiFiEvent_t event);
 
+void on_mqtt_connection(bool session);
+
 void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason);
 
 size_t construct_json(float *data, char *buffer, int buffer_size);

src/wlan.cpp

@@ -3,6 +3,7 @@
 void initialize_wlan() { WiFi.onEvent(wlan_connection_handler); }
 
 void initialize_mqtt() {
+    mqtt_client.onConnect(on_mqtt_connection);
     mqtt_client.onDisconnect(on_mqtt_disconnection);
     mqtt_client.setServer(config->mqtt_host, config->mqtt_port);
     mqtt_client.setCredentials(config->mqtt_user, config->mqtt_password);
@@ -31,6 +32,8 @@ void wlan_connection_handler(WiFiEvent_t event) {
     }
 }
 
+void on_mqtt_connection(bool session) { Serial.println("MQTT connected"); };
+
 void on_mqtt_disconnection(AsyncMqttClientDisconnectReason reason) {
     Serial.println("MQTT disconnected");