Return the reason for precentile early stop to log

[mindgamer]

Summary: We want to log the reason for percentile early stopping. Made changes to return the reason.

Differential Revision: D86737383

[meta-codesync[bot]]

@mindgamer has exported this pull request. If you are a Meta employee, you can view the originating Diff in D86737383.

[codecov-commenter]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 96.56%. Comparing base (5e80f0a) to head (7bd51e7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4523      +/-   ##
==========================================
- Coverage   96.56%   96.56%   -0.01%     
==========================================
  Files         546      546              
  Lines       56089    56094       +5     
==========================================
+ Hits        54165    54167       +2     
- Misses       1924     1927       +3     

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