
**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.



airflow/stats.py
"""Returns logger for statsd"""
        
        
        from statsd import StatsClient
        stats_class = conf.getimport('metrics', 'statsd_custom_client_path', fallback=None)
        if stats_class:
            if not issubclass(stats_class, StatsClient):
                raise AirflowConfigException(
                    "Your custom Statsd client must extend the statsd.StatsClient in order to ensure "
                    "backwards compatibility."
                )
            else:
                log.info("Successfully loaded custom Statsd client")
        else:
            stats_class = StatsClient
        statsd = stats_class(
            host=conf.get('metrics', 'statsd_host'),
            port=conf.getint('metrics', 'statsd_port'),
            prefix=conf.get('metrics', 'statsd_prefix'),
        )
        allow_list_validator = AllowListValidator(conf.get('metrics', 'statsd_allow_list', fallback=None))
        return SafeStatsdLogger(statsd, allow_list_validator)
    @classmethod
    def get_dogstatsd_logger(cls):