Metrics - DagRun Schedule Delay

### Apache Airflow version 2.6.2 ### What happened The timers `airflow_dagrun.<dag_id>.first_task_scheduling_delay` and `airflow_dagrun.schedule_delay.<dag_id>` both get emitted correctly in StatsD but not in OTel. I am submitting this as an Issue since I will be a little distracted for the next bit and figured someone may be able to have a look in the meantime. Please do not assign it to me, I'll get it when I can is nobody else does. ### What you think should happen instead Behavior should be consistent. ### How to reproduce To reproduce, you can run Breeze with the statsd or the otel integration (for example breeze start-airflow --integration otel) and run the following DAG, then open the [OTel](http://localhost:28889/metrics) or [StatsD](http://localhost:29102/metrics) raw data view to verify. ``` from airflow import DAG from airflow.decorators import task from airflow.utils.timezone import datetime @task def task1(): return 'Hello' @task def task2(): return 'World!' @task def task3(in1, in2): print(f'{in1} {in2}') with DAG( dag_id='taskflow_demo', start_date=datetime(2021, 1, 1), schedule=None, catchup=False ) as dag: task3(task1(), task2()) ``` You will see that OTel does emit `airflow_dagrun_first_task_scheduling_delay` and `airflow_dagrun_schedule_delay`with tags containing the dag_id, but it does not get the version of the matric which contains the embedded dag_id. This MIGHT be due to the name length restrictions in OTel but if that is the case then it should be emitting a truncated name, not dropping/ignoring it. ### Operating System ubuntu ### Versions of Apache Airflow Providers _No response_ ### Deployment Docker-Compose ### Deployment details _No response_ ### Anything else _No response_ ### Are you willing to submit PR? - [X] Yes I am willing to submit a PR! ### Code of Conduct - [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)