**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? -->

"""Get the number of active dag runs for each dag."""
        query = session.query(cls.dag_id, func.count("*"))
        if dag_ids is not None:
            
            
            query = query.filter(cls.dag_id.in_(list(set(dag_ids))))
        if only_running:
            query = query.filter(cls.state == State.RUNNING)
        else:
            query = query.filter(cls.state.in_([State.RUNNING, State.QUEUED]))
        query = query.group_by(cls.dag_id)
        return {dag_id: count for dag_id, count in query.all()}
    @classmethod
    def next_dagruns_to_examine(
        cls,
        state: DagRunState,
        session: Session,
        max_number: int | None = None,
    ) -> list[DagRun]:
        """
        Return the next DagRuns that the scheduler should attempt to schedule.
        This will return zero or more DagRun rows that are row-level-locked with a "SELECT ... FOR UPDATE"
        query, you should ensure that any scheduling decisions are made in a single transaction -- as soon as
        the transaction is committed it will be unlocked.
        """
        from airflow.models.dag import DagModel
        if max_number is None:
            max_number = cls.DEFAULT_DAGRUNS_TO_EXAMINE
        
        query = (