DAOS-15563 engine: Fix dss_chore use-after-free (#14096)

[jolivier23]

When dss_chore.cho_func returns DSS_CHORE_DONE, the dss_chore object may
have been freed already. For instance, in the dtx_rpc_helper case,
dtx_check may have already returned, freeing (strictly speaking,
releasing) its stack frame that contains the dca.dca_chore object.
Hence, after calling chore->cho_func, dss_chore_queue_ult should only
dereference chore if the return value is DSS_CHORE_YIELD.

Signed-off-by: Li Wei wei.g.li@intel.com

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[github-actions]

Bug-tracker data:
Ticket title is 'dss_chore_queue_ult segmentation fault during ec_multiple_rank_failure test'
Status is 'Resolved'
Labels: 'scrubbed'
https://daosio.atlassian.net/browse/DAOS-15563

[daosbuild1]

LGTM. No errors found by checkpatch.

[daosbuild1]

Test stage Functional on EL 8.8 completed with status UNSTABLE. https://build.hpdd.intel.com/job/daos-stack/job/daos//view/change-requests/job/PR-14196/1/testReport/

[daosbuild1]

LGTM. No errors found by checkpatch.

[daosbuild1]

LGTM. No errors found by checkpatch.