feat: ensure fms-acceleration callbacks run before TrainerController

[YashasviChaurasia]

Description of the change

This PR fixes the callback registration order in sft_trainer.py to ensure that fms-acceleration callbacks are registered before the TrainerController, essentially reordering the callbacks correctly.
This ensures on_save() from fms-acceleration executes first in order by registering fms-acceleration callbacks before TrainerControllerCallback

This is a required change because the fms-acceleration callbacks handle low-level checkpoint preparation — such as unwrapping model wrappers, merging adapter weights, and finalizing the model state before saving, when registering them before the TrainerControllerCallback, their on_save() runs first, ensuring checkpoints are complete and consistent.

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• I have added >=1 unit test(s) for every new method I have added.
• I have ensured all unit tests pass

[github-actions]

Thanks for making a pull request! 😃
One of the maintainers will review and advise on the next steps.

[dushyantbehl]

LGTM

[dushyantbehl]

Requesting clarification on slack on the design before merging

we will go with this for now, and will work on the dir as a separate PR.