**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? -->

self.log.warning("Failing (%s) jobs without heartbeat after %s", len(zombies), limit_dttm)
        for ti, file_loc, processor_subdir in zombies:
            zombie_message_details = self._generate_zombie_message_details(ti)
            request = TaskCallbackRequest(
                full_filepath=file_loc,
                processor_subdir=processor_subdir,
                simple_task_instance=SimpleTaskInstance.from_ti(ti),
                msg=str(zombie_message_details),
            )
            self.log.error("Detected zombie job: %s", request)
            self.executor.send_callback(request)
            Stats.incr(
                "zombies_killed", tags={"dag_id": ti.dag_id, "run_id": ti.run_id, "task_id": ti.task_id}
            )
    @staticmethod
    def _generate_zombie_message_details(ti: TaskInstance):
        zombie_message_details = {
            "DAG Id": ti.dag_id,
            "Task Id": ti.task_id,
            "Run Id": ti.run_id,
        }
        if ti.map_index != -1:
            zombie_message_details["Map Index"] = ti.map_index
        if ti.hostname:
            zombie_message_details["Hostname"] = ti.hostname
        if ti.external_executor_id:
            zombie_message_details["External Executor Id"] = ti.external_executor_id
        return zombie_message_details
    @provide_session
    def _cleanup_stale_dags(self, session: Session = NEW_SESSION) -> None: