DAOS-18976 rebuild: avoid to triggerFAIL_RECLAIM too early

[gnailzenh]

• avoids triggering FAIL_RECLAIM before SWIM updates pool map
• lets rebuild_scan_leader exit quickly so TLS cleanup unblocks before retry

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]

Ticket title is 'Aurora rebuild failing with DER_HG / DER_SHUTDOWN'
Status is 'In Progress'
Labels: 'test_2.6.5rc1'
https://daosio.atlassian.net/browse/DAOS-18976

[daosbuild3]

Test stage Build RPM on Leap 15 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18289/1/execution/node/318/log

[daosbuild3]

Test stage Test RPMs on Leap 15.5 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18289/1/execution/node/1159/log