Update AUROC checks for CBPE and realized performance

[nikml]

• All classes need to be present to fit and to calculate realized performance for a chunk.

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 77.18%. Comparing base (b25655a) to head (d353276).
Report is 5 commits behind head on main.

Files	Patch %	Lines
...e_calculation/metrics/multiclass_classification.py	83.33%	4 Missing ⚠️
...performance_estimation/confidence_based/metrics.py	91.30%	2 Missing ⚠️
...ml/performance_estimation/confidence_based/cbpe.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #405      +/-   ##
==========================================
+ Coverage   77.00%   77.18%   +0.18%     
==========================================
  Files         108      108              
  Lines        9300     9314      +14     
  Branches     1655     1657       +2     
==========================================
+ Hits         7161     7189      +28     
+ Misses       1677     1664      -13     
+ Partials      462      461       -1     

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