Fix topk emitted batches

[cetra3]

Which issue does this PR close?

• Closes SortExec (TopK) output_batches metric does not match the number of emitted batches #24468
• Closes PartitionedTopKExec does not expose any metrics (metrics() returns None) #24470

Rationale for this change

Fixes some issues around metrics and TopK execution nodes

What changes are included in this PR?

Adjusts to include metrics in PartitionedTopKExec and also fixes the batch count in TopK

Are these changes tested?

Yes new tests added.

Are there any user-facing changes?

No new traits, etc.. just fixes some bugs on the physical plan side

[codecov-commenter]

Codecov Report

❌ Patch coverage is 87.17949% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.24%. Comparing base (c429919) to head (e88598c).

Files with missing lines	Patch %	Lines
datafusion/physical-plan/src/topk/mod.rs	86.66%	5 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #24481      +/-   ##
==========================================
- Coverage   81.24%   81.24%   -0.01%     
==========================================
  Files        1113     1113              
  Lines      392744   392816      +72     
  Branches   392744   392816      +72     
==========================================
+ Hits       319090   319145      +55     
- Misses      54900    54909       +9     
- Partials    18754    18762       +8     

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