DAOS-18859 test: No fix

[knard38]

Add D_ERROR + fprintf(stderr) diagnostic messages in kv_put() and kv_get() that fire when daos_eq_poll() returns rc < 0 (poll error) and the code is about to dereference the stale evp pointer.

This commit does NOT fix the bug — it only makes it visible in CI logs. When triggered, the messages confirm the stale-evp condition occurred, helping correlate with subsequent SIGSEGV or ASAN errors.

Quick-Functional: true
Test-repeat: 5
Test-tag: PoolAutotestTest,test_pool_autotest

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 'pool/autotest.py:PoolAutotestTest.test_pool_autotest - segmentation violation'
Status is 'In Progress'
Labels: 'ci_2.8_daily,daily_test,scrubbed_2.8'
https://daosio.atlassian.net/browse/DAOS-18859

[daosbuild3]

Test stage Functional Hardware 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-18322/1/execution/node/740/log