fix: copy include/ artifacts back to host after astro dev pytest

[tayloramurphy]

Summary

• Fixes Artifacts generated during astro dev pytest are not available after tests have finished #2066: after astro dev pytest finishes, files written to include/ (e.g. --junit-xml=include/pytest_report.junit.xml) are once again accessible on the host.
• Uses docker cp instead of bind-mounts for pytest #2036 replaced the pytest bind mounts with a forward docker cp loop but never added a reverse copy, so artifacts stayed stranded inside the container.
• Scope is intentionally limited to the documented contract at https://www.astronomer.io/docs/astro/cli/astro-dev-pytest — only include/ is copied back, not dags/, tests/, or plugins/.

Implementation notes

• After the pytest container runs, docker cp astro-pytest:/usr/local/airflow/include/. <airflowHome>/include restores artifact visibility on the host.
• The reverse copy is skipped when the host has no include/ directory, so docker cp never errors on projects without one.
• Errors are logged at debug level (same pattern used for the HTML report copy and the final rm) so an unexpected cp failure does not mask the real pytest exit code.

Test plan

• go test ./airflow/ -run 'TestAirflow/TestDockerImagePytest' -v -count=1 — all existing pytest subtests pass, plus two new ones:
  • copies include/ back to host after test run — asserts the reverse cp targets astro-pytest:/usr/local/airflow/include/. → <airflowHome>/include and runs after start.
  • skips reverse include/ copy when host include/ does not exist — asserts no reverse cp is attempted when the host directory is absent.
• go test ./airflow/ -count=1 — full airflow package passes.
• Manual verification on a real project: astro dev pytest --args '--junit-xml=include/pytest_report.junit.xml' followed by file include/pytest_report.junit.xml to confirm the artifact is present.