[Flux2] Fix LoRA loading for Flux2 Klein by adaptively enumerating transformer blocks (#13030)
* Resolve Flux2 Klein 4B/9B LoRA loading errors
* Apply style fixes
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Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>