DAOS-19212 container: check container before creating cont_track_eph_…

[liuxuezhao]

…leader

In ds_cont_leader_update_track_eph(), check container's existence before creating cont_track_eph_leader. Because for orphan container case the other engine possibly reports its track_eph to leader, leader should check container's valid in that case.

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: performance jobs keep timing out with v2.8.0-rc1 and MDonSSD'
Status is 'In Progress'
Labels: '2.8.0rc1,md_on_ssd,request_for_2.8,scrubbed_2.8,test_2.8.0rc'
https://daosio.atlassian.net/browse/DAOS-19212

[daosbuild3]

Test stage Test RPMs on EL 9.6 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18628/4/execution/node/1254/log

[daosbuild3]

Test stage Test RPMs on EL 9.6 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18628/5/execution/node/1254/log

[daosbuild3]

Test stage Functional Hardware Medium 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-18628/6/testReport/

[daosbuild3]

Test stage Functional Hardware Medium Verbs Provider 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-18628/7/testReport/