fix: Return specific error code when encountering incomplete requery results

[bigsheeper]

During requery, segments may change (e.g., due to compaction), so we need to return specific error codes when encountering incomplete requery results. Clients can then retry to avoid this issue.

issue: #29656

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 81.03%. Comparing base (17b4938) to head (e5bfd2a).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #31343      +/-   ##
==========================================
- Coverage   81.04%   81.03%   -0.01%     
==========================================
  Files         980      980              
  Lines      143314   143320       +6     
==========================================
- Hits       116147   116139       -8     
- Misses      23273    23280       +7     
- Partials     3894     3901       +7     

Files	Coverage Δ
pkg/util/merr/errors.go	85.71% <ø> (ø)
pkg/util/merr/utils.go	89.33% <100.00%> (+0.09%)	⬆️
internal/proxy/task_search.go	83.98% <0.00%> (ø)

... and 32 files with indirect coverage changes

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bigsheeper, czs007

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• internal/proxy/OWNERS [czs007]
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