DAOS-17576 chk: keep orphan pool shard which status is DOWN or DOWNOUT

[Nasf-Fan]

When check engine verifies pool membership, it may discard the rank or target which status is ‘DOWN' or 'DOWNOUT’ to release related space. Such logic was fine before. But as incremental reintegration feature is on the way, such logic needs to be improved; otherwise, if related orphan pool shard is removed by check engine, subsequent reintegration has to be started from the scratch instead of incremental work.

Test-tag: cat_recov

Steps for the author:

• [ ] Commit message follows the guidelines.
• [ ] Appropriate Features or Test-tag pragmas were used.
• [ ] Appropriate Functional Test Stages were run.
• [ ] At least two positive code reviews including at least one code owner from each category referenced in the PR.
• [ ] Testing is complete. If necessary, forced-landing label added and a reason added in a comment.

After all prior steps are complete:

• [ ] Gatekeeper requested (daos-gatekeeper added as a reviewer).

[github-actions[bot]]

Ticket title is 'Do not discard orphan pool shard which status is DOWN or DOWNOUT' Status is 'In Progress' https://daosio.atlassian.net/browse/DAOS-17576

[daosbuild3]

Test stage NLT on EL 8.8 completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-16394/3/testReport/