Fix oper-state queries that involve choice/case nodes (backport #18231)

[mergify]

Add additional unit-test cases to cover the found issues

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This is an automatic backport of pull request #18231 done by Mergify.

[mergify]

Cherry-pick of b9ff10b has failed:

On branch mergify/bp/stable/10.1/pr-18231
Your branch is up to date with 'origin/stable/10.1'.

You are currently cherry-picking commit b9ff10b08.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   lib/northbound_oper.c

no changes added to commit (use "git add" and/or "git commit -a")

Cherry-pick of 73df7da has failed:

On branch mergify/bp/stable/10.1/pr-18231
Your branch is ahead of 'origin/stable/10.1' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 73df7da40.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   tests/lib/northbound/test_oper_data.in
	both modified:   tests/lib/northbound/test_oper_data.refout

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally