DAOS-14976 object: properly select collective punch leader for resend

[Nasf-Fan]

Before resending the collective punch RPC, we need to check whether the original leader shard is valid or not. It is possible the object layout has been shrinked after rebuild. Under such case, select a new shard as the collective punch leader.

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[github-actions]

Bug-tracker data:
Ticket title is 'FTEST_daos_test.DaosCoreTest-DAOS_Rebuild_Simple.REBUILD27 - 0x16 != 0'
Status is 'In Progress'
Labels: 'ci_impact,pr_test,triaged'
https://daosio.atlassian.net/browse/DAOS-14976

[daosbuild1]

Test stage Functional Hardware Medium completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-13602/1/testReport/

[Nasf-Fan]

PoolCreateTests.test_create_no_space_loop failed for DAOS-14884, not related with the patch.

[wangshilong]

it looks to me spa->pa_auxi.shard != obj->cob_shards_nr looks more safe, shard might be extended after rebuild as well?

[Nasf-Fan]

It is no matter if the object layout is extended, because under extended case, the shard with index "spa->pa_auxi.shard" will not disappear, it still can be used as the leader.

[wangshilong]

Indeed, thanks for explain.