Don't apply labels normalization on training

[sovrasov]

Fix h-cls training when labels normalization is required

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.65%. Comparing base (9c88dec) to head (e8f3b56).
Report is 2 commits behind head on releases/1.6.0.

Additional details and impacted files

@@                Coverage Diff                 @@
##           releases/1.6.0    #3886      +/-   ##
==================================================
- Coverage           80.65%   80.65%   -0.01%     
==================================================
  Files                 536      536              
  Lines               40552    40554       +2     
==================================================
+ Hits                32708    32709       +1     
- Misses               7844     7845       +1     

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[yunchu]

@chuneuny-emily @sovrasov @harimkang please don't forget to add your changes to the CHANGELOG.md
if you missed it, we need to create another PR to update that.