**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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import warnings
from collections import defaultdict
from datetime import datetime, timedelta
from pathlib import Path
from typing import TYPE_CHECKING, Collection, DefaultDict, Iterator
from sqlalchemy import and_, func, not_, or_, text
from sqlalchemy.exc import OperationalError
from sqlalchemy.orm import load_only, selectinload
from sqlalchemy.orm.session import Session, make_transient
from sqlalchemy.sql import expression
from airflow import settings
from airflow.callbacks.callback_requests import DagCallbackRequest, SlaCallbackRequest, TaskCallbackRequest
from airflow.callbacks.pipe_callback_sink import PipeCallbackSink
from airflow.configuration import conf
from airflow.exceptions import RemovedInAirflow3Warning
from airflow.executors.executor_loader import ExecutorLoader
from airflow.jobs.base_job import BaseJob
from airflow.models.dag import DAG, DagModel
from airflow.models.dagbag import DagBag
from airflow.models.dagrun import DagRun
from airflow.models.dataset import (
    DagScheduleDatasetReference,
    DatasetDagRunQueue,
    DatasetEvent,
    DatasetModel,
    TaskOutletDatasetReference,
)
from airflow.models.serialized_dag import SerializedDagModel
from airflow.models.taskinstance import SimpleTaskInstance, TaskInstance, TaskInstanceKey
from airflow.stats import Stats