[DISC] always auto-discover Presence/Tracker timeout (#1959)

auto-discover Presence/Tracker timeout even when HASS presence is not active

Also inject an additional placeholder rssi key and value into the BM2 voltage connection message to avoid the message being registered as a device tracker AWAY

https://community.openmqttgateway.com/t/bm2-home-and-away/3315

main/ZgatewayBLEConnect.ino

@@ -301,6 +301,8 @@ void BM2_connect::notifyCB(NimBLERemoteCharacteristic* pChar, uint8_t* pData, si
       float volt = ((output[2] | (output[1] << 8)) >> 4) / 100.0f;
       BLEdata["volt"] = volt;
       Log.trace(F("volt: %F" CR), volt);
+      // to avoid the BM2 device tracker going offline because of the voltage MQTT message without an RSSI value
+      BLEdata["rssi"] = -60;
       buildTopicFromId(BLEdata, subjectBTtoMQTT);
       handleJsonEnqueue(BLEdata, QueueSemaphoreTimeOutTask);
     } else {