Fixing the pipeline optimization by reindexing targets (V2)
Author: Narsil
Pull request: yes

# What does this PR do?

Linked to #12329
Other version that keeps the scores original (meaning you could have mostly 0.0 for unprobable tokens.

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Fixes # (issue)


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Comments:
@LysandreJik pulled your tests, thanks !

Yeah it looks good, thanks!

Thanks @guyrosin!