**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? -->

non_orphaned_dataset_count = session.query(DatasetModel).filter(~DatasetModel.is_orphaned).count()
        assert non_orphaned_dataset_count == 4
        orphaned_dataset_count = session.query(DatasetModel).filter(DatasetModel.is_orphaned).count()
        assert orphaned_dataset_count == 0
        
        with dag_maker(dag_id="datasets-1", schedule=[dataset1], session=session):
            BashOperator(task_id="task", bash_command="echo 1", outlets=[dataset3])
        self.scheduler_job = SchedulerJob(subdir=os.devnull)
        self.scheduler_job._orphan_unreferenced_datasets(session=session)
        session.flush()
        
        non_orphaned_datasets = [
            dataset.uri
            for dataset in session.query(DatasetModel.uri)
            .filter(~DatasetModel.is_orphaned)
            .order_by(DatasetModel.uri)
        ]
        assert non_orphaned_datasets == ["ds1", "ds3"]
        orphaned_datasets = [
            dataset.uri
            for dataset in session.query(DatasetModel.uri)
            .filter(DatasetModel.is_orphaned)
            .order_by(DatasetModel.uri)
        ]
        assert orphaned_datasets == ["ds2", "ds4"]
@pytest.mark.need_serialized_dag
def test_schedule_dag_run_with_upstream_skip(dag_maker, session):
    """
    Test if _schedule_dag_run puts a task instance into SKIPPED state if any of its
    upstream tasks are skipped according to TriggerRuleDep.