fix: Fix sorting buffer in clustering compaction

[xiaocai2333]

issue: #28410

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 80.90%. Comparing base (c2855a5) to head (c93a06d).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
...ternal/datanode/compaction/clustering_compactor.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #38417      +/-   ##
==========================================
+ Coverage   80.89%   80.90%   +0.01%     
==========================================
  Files        1376     1376              
  Lines      193089   193089              
==========================================
+ Hits       156198   156226      +28     
+ Misses      31359    31339      -20     
+ Partials     5532     5524       -8     

Components	Coverage Δ
Client	74.58% <ø> (ø)
Core	68.91% <ø> (ø)
Go	83.02% <0.00%> (+0.01%)	⬆️

Files with missing lines	Coverage Δ
...ternal/datanode/compaction/clustering_compactor.go	65.54% <0.00%> (ø)

... and 17 files with indirect coverage changes

[czs007]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: czs007, xiaocai2333

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