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 69.01%. Comparing base (fb39755) to head (93f5392).

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   69.01%   69.01%           
=======================================
  Files        1482     1482           
  Lines      273999   273999           
  Branches    28258    28258           
=======================================
  Hits       189093   189093           
+ Misses      77520    77516    -4     
- Partials     7386     7390    +4     

Flag	Coverage Δ
Debug	69.01% <0.00%> (ø)
production	63.30% <0.00%> (ø)
test	89.46% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

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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