[v3-3-test] Fix conn-fields check crash for nested provider packages (#70224)

[Lee-W]

(cherry picked from commit c578603)

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[Lee-W]

ideally, we shouldn't need this one but we might sometimes backport PR with provider changes and core-change. so backport this for preventing unexpected CI failure

[vatsrahul1001]

@Lee-W looks like we have some conflicts

[Lee-W]

opps, didn't notice it. let me fix it now

[potiuk]

Backport verified against #70224 — the three atlassian/jira hunks and the common_prek_utils.py change are byte-identical to what merged on main, no cherry-pick drift.

Worth recording why this carries 4 of the 5 files: the omitted scripts/ci/prek/check_provider_yaml_files.py hunk was superseded on main by #70261, which replaced the KNOWN_SECOND_LEVEL_PATHS prefix-guessing with a real directory-tree walk via get_provider_base_dir_from_path(). That follow-up is already on v3-3-test, so porting #70224's version here would have regressed the resolver rather than fixed it. Dropping it is the right call.

The "ibm" entry still matters independently of the resolver — check_providers_subpackages_all_have_init.py and mypy_folder.py both still read that list, and providers/ibm/mq is a real nested package.

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Drafted-by: Claude Code (Opus 5); reviewed by @potiuk before posting