Fix gradient-checkpointing option is ignored in SDXL+LoRA training. (#6388) (#6402)
* Fix gradient-checkpointing option is ignored in SDXL+LoRA training. (#6388)
* Fix gradient-checkpointing option is ignored in SD+LoRA training.
* Fix gradient checkpoint is not applied to text encoders. (SDXL+LoRA)
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Co-authored-by: Sayak Paul <spsayakpaul@gmail.com>