Flag conn-fields in hook but absent from provider.yaml in static checks

[dabla]

The check_conn_fields_match_form_widgets static check introduced in #69473
only validated one direction: stale keys declared in conn-fields (YAML) that no
longer exist in get_connection_form_widgets(). It did not catch the opposite
case — a field added to the hook's form widgets but forgotten in conn-fields —
which means the field silently disappears from the new React connection UI.

PR #64643 (Samba auth_protocol) exposed this gap: auth_protocol was added to
get_connection_form_widgets() but not to conn-fields in provider.yaml, and
the check passed without complaint.

The fix makes the check bidirectional: when conn-fields is declared, its keys
must exactly match the hook's widget keys. Both directions are now reported as
errors with distinct fix hints. The "no conn-fields at all" case is still
silently skipped (opting out of the React UI form is intentional).

---

Was generative AI tooling used to co-author this PR?

• [ x ] Yes (please specify the tool below)

Claude Sonnet 4.6

---

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[github-actions]

uv.lock on main just moved via #69694 ("[main] Upgrade important CI environment"), commit c8d313a and this PR currently conflicts.

Quickest fix:

git fetch upstream main && git rebase upstream/main
rm uv.lock && uv lock
git add uv.lock && git rebase --continue
git push --force-with-lease

Automated nudge — ignore if you're not ready to rebase. This comment is updated in place on future uv.lock bumps.

[jason810496]

LGTM once the CI pass, thanks.

[github-actions]

Backport failed to create: v3-3-test. View the failure log Run details

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
❌	v3-3-test

You can attempt to backport this manually by running:

cherry_picker 58b5a80 v3-3-test

This should apply the commit to the v3-3-test branch and leave the commit in conflict state marking
the files that need manual conflict resolution.

After you have resolved the conflicts, you can continue the backport process by running:

cherry_picker --continue

If you don't have cherry-picker installed, see the installation guide.

[dabla]

Backport to v3-3-test succeeded via PR #69996 .