
**Apache Airflow version**:
2.0.0

**Environment**:

- **OS** (e.g. from /etc/os-release): Ubuntu 20.04 LTS
- **Python version**: 3.8
- **Kernel** (e.g. `uname -a`): x86_64 x86_64 x86_64 GNU/Linux 5.4.0-58-generic #64-Ubuntu
- **Install tools**: pip


**What happened**:

Airflow 2.0 does not send metrics to statsD.

I configure Airflow with official documentation (https://airflow.apache.org/docs/apache-airflow/stable/logging-monitoring/metrics.html) and by this article https://dstan.medium.com/run-airflow-statsd-grafana-locally-16b372c86524 (but I used port 8125). 

I turned on statsD:

```ini
statsd_on = True
statsd_host = localhost
statsd_port = 8125
statsd_prefix = airflow
```

But I do not see airflow metrics at http://localhost:9102/metrics (statsD metrics endpoint).

---

P.S. I noticed this error just using Airflow 2.0. In version 1.10.13 everything is ok in the same environment.

Thank you for advance.



tests/core/test_stats.py
#
#
#
import importlib
import re
import unittest
from unittest import mock
from unittest.mock import Mock
import pytest
import statsd
import airflow
from airflow.exceptions import AirflowConfigException, InvalidStatsNameException
from airflow.stats import AllowListValidator, SafeDogStatsdLogger, SafeStatsdLogger
from tests.test_utils.config import conf_vars
class CustomStatsd(statsd.StatsClient):
    incr_calls = 0
    def __init__(self, host=None, port=None, prefix=None):
        super().__init__()
    def incr(self, stat, count=1, rate=1):  
        CustomStatsd.incr_calls += 1
    @classmethod
    def _reset(cls):
        cls.incr_calls = 0
class InvalidCustomStatsd: