Revert "DAOS-17444 rebuild: cache obj open handle for rebuild (#16373)"

[liuxuezhao]

This reverts commit d9f7d83.

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 'Rebuild performance improvements'
Status is 'In Progress'
Labels: 'ALCF,alcf_track,aurora_post_at,hpe_cluster,scrubbed_2.6.5,scrubbed_2.8,test_rebuild'
Job should run at elevated priority (1)
https://daosio.atlassian.net/browse/DAOS-17444

[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-17395/1/testReport/

[daosbuild3]

Test stage Functional Hardware Large MD on SSD completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-17395/1/testReport/