**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**

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from airflow.ti_deps.dependencies_states import EXECUTION_STATES
from airflow.timetables.simple import DatasetTriggeredTimetable
from airflow.utils import timezone
from airflow.utils.event_scheduler import EventScheduler
from airflow.utils.retries import MAX_DB_RETRIES, retry_db_transaction, run_with_db_retries
from airflow.utils.session import NEW_SESSION, create_session, provide_session
from airflow.utils.sqlalchemy import (
    CommitProhibitorGuard,
    is_lock_not_available_error,
    prohibit_commit,
    skip_locked,
    tuple_in_condition,
    with_row_locks,
)
from airflow.utils.state import DagRunState, State, TaskInstanceState
from airflow.utils.types import DagRunType
if TYPE_CHECKING:
    from types import FrameType
    from airflow.dag_processing.manager import DagFileProcessorAgent
TI = TaskInstance
DR = DagRun
DM = DagModel
def _is_parent_process() -> bool:
    """
    Whether this is a parent process.
    Return True if the current process is the parent process.
    False if the current process is a child process started by multiprocessing.
    """
    return multiprocessing.current_process().name == "MainProcess"
class SchedulerJob(BaseJob):