fix: the retrieve plan on heap is used after free when reduce

[chyezh]

issue: #38731
pr: #38840

[congqixia]

/lgtm

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[codecov]

Codecov Report

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

Project coverage is 80.37%. Comparing base (fec92e9) to head (49b2cec).
Report is 3 commits behind head on 2.4.

Files with missing lines	Patch %	Lines
internal/querynodev2/segments/result.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #38842      +/-   ##
==========================================
- Coverage   83.37%   80.37%   -3.01%     
==========================================
  Files         809     1077     +268     
  Lines      143064   169559   +26495     
==========================================
+ Hits       119281   136276   +16995     
- Misses      19299    28797    +9498     
- Partials     4484     4486       +2     

Files with missing lines	Coverage Δ
internal/querynodev2/segments/result.go	69.68% <0.00%> (ø)

... and 297 files with indirect coverage changes