Bulk-clear path for `airflow dags clear` to avoid N transactions

[Lee-W]

Body

airflow dags clear (#66004) loops Dag.clear(run_id=...) per matched run, so a wide --partition-date-* window or broad --partition-key costs N transactions.

Reusing Dag.clear() was deliberate (identical TI reset / re-queue semantics); a true bulk path needs its own design — single TX or batched per airflow-core/src/airflow/utils/db_cleanup.py. Switch the per-run loop to it once available.

Raised in #66004 (comment).

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.