DAOS-19396 pool: mind pool_discard() dss_rpc_send() errors

[kccain]

Experimental product code change on release/2.6 branch to not proceed to pool map update step of ds_pool_update_handler() for reintegration operations when the previous pool_discard() step got an error in dss_rpc_send() (e.g., a -DER_TIMEDOUT failure).

This gives retries either by the MS host daos_engine dsc_pool_client or by the test program itself (re-issuing the dmg pool reintegrate command) a chance to wait out and possibly recover from whatever communication failures are occurring among some engines and the reintegrating engine.

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).

[daosbuild3]

Test stage Build RPM on Leap 15.5 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18894/1/execution/node/308/log

[daosbuild3]

Test stage Build RPM on EL 9 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18894/1/execution/node/394/log

[daosbuild3]

Test stage Build RPM on EL 8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net//job/daos-stack/job/daos/view/change-requests/job/PR-18894/1/execution/node/429/log

[daosbuild3]

Test stage Unit Test bdev on EL 8.8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/job/PR-18894/1/display/redirect

[daosbuild3]

Test stage Unit Test bdev with memcheck on EL 8.8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/job/PR-18894/1/display/redirect

[daosbuild3]

Test stage Unit Test on EL 8.8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/job/PR-18894/1/display/redirect

[daosbuild3]

Test stage Unit Test with memcheck on EL 8.8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/job/PR-18894/1/display/redirect

[daosbuild3]

Test stage NLT on EL 8.8 completed with status FAILURE. https://jenkins-3.daos.hpc.amslabs.hpecorp.net/job/daos-stack/job/daos/job/PR-18894/1/display/redirect

[github-actions]

Ticket title is 'daos_test/suite.py:DaosCoreTest.test_daos_rebuild_ec - pool reintegrate timeout'
Status is 'In Progress'
Labels: '2.6.5.p2rc1,pr_test,testp1'
https://daosio.atlassian.net/browse/DAOS-19396