Fix PositiveRecall optimization in AutoMLExperiment

[JoshuaSloan]

BinaryClassificationMetric.PositiveRecall incorrectly returns PositivePrecision.

I noticed this when testing an early stopping pipeline and found that the logged best trial metric did not align with the final model results. This is a self-evident fix (akin to a small typo), so I did not open a new issue for it.

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 68.99%. Comparing base (d9694c4) to head (4fcb375).

Files with missing lines	Patch %	Lines
...osoft.ML.AutoML/AutoMLExperiment/IMetricManager.cs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7493      +/-   ##
==========================================
- Coverage   69.00%   68.99%   -0.01%     
==========================================
  Files        1482     1482              
  Lines      273901   273901              
  Branches    28256    28256              
==========================================
- Hits       189000   188989      -11     
- Misses      77514    77522       +8     
- Partials     7387     7390       +3     

Flag	Coverage Δ
Debug	68.99% <0.00%> (-0.01%)	⬇️
production	63.29% <0.00%> (-0.01%)	⬇️
test	89.45% <ø> (ø)

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Files with missing lines	Coverage Δ
...osoft.ML.AutoML/AutoMLExperiment/IMetricManager.cs	51.76% <0.00%> (ø)

... and 6 files with indirect coverage changes

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