**Description**


It would be great if the metrics we publish in Airflow change to include TAGs for "variable" parts of those (such as dag_id, task_id, pool name) rather than being part of the metrics.

See here: https://airflow.apache.org/docs/1.10.12/metrics.html, https://airflow.readthedocs.io/en/latest/logging-monitoring/metrics.html  - those variable parts should be tags.

We might consider to change those metrics by default in 2.0 and possibly introduce a backport in 1.10.13 to allow people to migrate.


**Use case / motivation**

Having the variable parts of the metrics makes it really difficult to aggregate the metrics. Seems that statsd python library does not support tags, but there are possible solutions by installing extensions:

https://stackoverflow.com/questions/49852654/sending-statsd-metrics-with-tags-from-python-client

**Related Issues**

<!-- Is there currently another issue associated with this? -->

"""Sync metadata from stat queue and only keep the latest stat."""
        self._done = stat.done
        self._all_files_processed = stat.all_files_processed
        self._last_parsing_stat_received_at = time.monotonic()
    @property
    def done(self) -> bool:
        """Whether the DagFileProcessorManager finished."""
        return self._done
    @property
    def all_files_processed(self):
        """Whether all files been processed at least once."""
        return self._all_files_processed
    def terminate(self):
        """Send termination signal to DAG parsing processor manager to terminate all DAG file processors."""
        if self._process and self._process.is_alive():
            self.log.info("Sending termination message to manager.")
            try:
                self._parent_signal_conn.send(DagParsingSignal.TERMINATE_MANAGER)
            except ConnectionError:
                pass
    def end(self):