perf: avoid clone and sort fast in TopK heap

[MassivePizza]

Which issue does this PR close?

• Closes TopKRow ordering is inconsistent, preventing a possible sort optimization #24659.

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 97.14286% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 81.58%. Comparing base (4d3e79e) to head (0f10041).
⚠️ Report is 27 commits behind head on main.

Files with missing lines	Patch %	Lines
datafusion/physical-plan/src/topk/mod.rs	96.42%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24639      +/-   ##
==========================================
+ Coverage   81.48%   81.58%   +0.09%     
==========================================
  Files        1122     1123       +1     
  Lines      404248   406620    +2372     
  Branches   404248   406620    +2372     
==========================================
+ Hits       329390   331722    +2332     
+ Misses      55547    55461      -86     
- Partials    19311    19437     +126     

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