DAOS-18866 vos: return nonexist error

[NiuYawei]

vos_obj_incarnate() should return DER_NONEXIST error when CREATE flag isn't present.

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 'ior/hard.py:IorHardBasic.test_ior_hard - ior No space left on device'
Status is 'In Progress'
Labels: 'ci_master_weekly,ucx_provider,weekly_test'
https://daosio.atlassian.net/browse/DAOS-18866

[Nasf-Fan]

The patch is fine. But I cannot understand why the original logic will cause PMEM trouble.

[janekmi]

This patch looks ok-ish but:

1. This very odd such a bug won't cause a lot more serious issues.
2. It is a little frightening we do not have a unit test covering this scenario.
3. This does not solve the DAOS-18866 issue but something interesting has happened. For the first time I see one of the test cases actually PASSed. Till now either all of them have failed or all of them have PASSed. I will re-test to confirm this effect.

Ref: https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/view/change-requests/job/PR-18192/13/testReport/FTEST_ior/IorHardBasic/

[NiuYawei]

This patch looks ok-ish but:

1. This very odd such a bug won't cause a lot more serious issues.

2. It is a little frightening we do not have a unit test covering this scenario.

3. **This does not solve the DAOS-18866 issue** but something interesting has happened. For the first time I see one of the test cases actually PASSed. Till now either all of them have failed or all of them have PASSed. I will re-test to confirm this effect.

Ref: https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/view/change-requests/job/PR-18192/13/testReport/FTEST_ior/IorHardBasic/

Thanks @janekmi . I guess it could be related to the unconditional punch changes. I updated to PR to return -DER_NONEXIST before starting tx when possible (which mimics the original behavior), could retry and see if it could fully solve the issue? Thanks in advance.