**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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num_errors,
                    f"{last_runtime:.2f}s" if last_runtime else None,
                    last_run.strftime("%Y-%m-%dT%H:%M:%S") if last_run else None,
                )
            )
        log_str = (
            "\n"
            + "=" * 80
            + "\n"
            + "DAG File Processing Stats\n\n"
            + tabulate(formatted_rows, headers=headers)
            + "\n"
            + "=" * 80
        )
        self.log.info(log_str)
    def get_pid(self, file_path) -> int | None:
        """
        Retrieve the PID of the process processing the given file or None if the file is not being processed.
        :param file_path: the path to the file that's being processed
        """
        if file_path in self._processors:
            return self._processors[file_path].pid
        return None
    def get_all_pids(self) -> list[int]:
        """
        Get all pids.
        :return: a list of the PIDs for the processors that are running
        """
        return [x.pid for x in self._processors.values()]
    def get_last_runtime(self, file_path) -> float | None: