DAOS-15827 vos: shrink committed DTX table size

[Nasf-Fan]

For committed DTX entry, only cache transaction ID in DRAM. The other information, such as DTX epoch and committed time will only be stored on disk persistently. On the other hand, since DTX ID is small enough as to it can be saved as the key for committed DTX btree without more payload in DRAM, then original 44-byte vos_dtx_cmt_ent is completedly removed from DRAM. That much shrinks committed DTX table size.

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 'Only cache necessary information in DRAM for active DTX entry'
Status is 'In Progress'
Labels: 'md_on_ssd2'
https://daosio.atlassian.net/browse/DAOS-15827

[daosbuild3]

Test stage Unit Test completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18840/3/testReport/

[daosbuild3]

Test stage Unit Test with memcheck completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18840/3/testReport/

[daosbuild3]

Test stage Unit Test bdev completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18840/4/testReport/

[daosbuild3]

Test stage Unit Test completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18840/4/testReport/

[daosbuild3]

Test stage Unit Test with memcheck completed with status UNSTABLE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos//view/change-requests/job/PR-18840/4/testReport/

[daosbuild3]

Test stage Functional Cluster Box Medium MD on SSD completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18840/4/execution/node/1536/log

[daosbuild3]

Test stage Functional Hardware Large MD on SSD completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18840/4/execution/node/1589/log