Switch plotting order for pr curves

[SkafteNicki]

What does this PR do?

Fixes #2161
Switch order to be consistent with scikit-learn

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• Did you make sure to update the docs?
• Did you write any new necessary tests?

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📚 Documentation preview 📚: https://torchmetrics--2183.org.readthedocs.build/en/2183/

[codecov]

Codecov Report

Merging #2183 (b83aaa7) into master (28ac2b2) will decrease coverage by 39%.
The diff coverage is 0%.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2183     +/-   ##
========================================
- Coverage      87%     47%    -39%     
========================================
  Files         293     293             
  Lines       16411   16417      +6     
========================================
- Hits        14267    7798   -6469     
- Misses       2144    8619   +6475