Move fixture hooks to runtest docs section

[ishaanlabs-gg]

Summary

• Move pytest_fixture_setup and pytest_fixture_post_finalizer from Reporting hooks to Test running (runtest) hooks.
• Keep pytest_runtest_logreport in Reporting hooks, matching the maintainer guidance in Docs: collection hooks listed under reporting hooks #12658.

Fixes part of #12658.

Testing

• Verified the two fixture hook entries now appear in the runtest section only.
• Ran git diff --check for doc/en/reference/reference.rst.

I did not run the full docs build locally because the available repo-local venv does not include Sphinx or Docutils.