List only .zip archives as packaged Dags

[jason810496]

Stack (bottom to top): #73970, #73971, #73972, #73973, #73974, #73975, #73976, #73977, #74030, #74031, #74032, #74033, #74067

Why

Dag discovery lists every zip archive as a packaged Dag, whatever its name. A JAR is a zip archive, so the Lang-SDK task-handler JARs and their dependency JARs in a Dag bundle are all listed as Dag files. Each gets a parse child every min_file_process_interval that finds no importer for .jar, and each bundle refresh opens it and checks every member. That work is wasted.

What changes

A zip archive is listed as a packaged Dag only when its name ends in .zip, so listing matches what an importer can import. This applies to list_py_file_paths, which the Dag processor uses to list a bundle's files. DagBag already lists by suffix through the Task SDK importers (#73853), where only .zip goes to the zip importer. .py files are listed as before.

dags/
  etl.py                  listed
  packaged.zip            listed
  reports.ZIP             listed
  handlers/etl.jar        no longer listed
  handlers/archive        no longer listed (a zip archive with no suffix)

• dags.rst now says a packaged Dag's file name must end in .zip.
• The might_contain_dag heuristic and the manager's per-archive member scan are unchanged.

How to test

uv run --project airflow-core --with-editable shared/secrets_masker pytest airflow-core/tests/unit/utils/test_file.py airflow-core/tests/unit/dag_processing/test_dagbag.py airflow-core/tests/unit/dag_processing/test_manager.py -q

Ran:

• test_file.py and test_dagbag.py: 96 passed, 1 skipped. test_manager.py: 208 passed, 6 skipped (Postgres and MySQL only).
• The new test fails without the change: a .jar archive and a zip archive with no suffix are listed next to the .zip and .ZIP ones.
• prek run --files on the changed files passed, and so did mypy-airflow-core.

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[jedcunningham]

This should get a significant newsfragment as it could potentially be breaking for some folks.

[jason810496]

Closing this: #74020 made it unnecessary. Dag files are now listed through the Task SDK importers by suffix, where only a .zip archive goes to the zip importer, and the two functions this PR edited (list_py_file_paths and find_dag_file_paths) are gone from main. Thanks @jedcunningham for the review: the significant newsfragment you asked for is no longer needed, since no behaviour change ships from this PR.