Revert deepspeed z3 regressions
Author: winglian
Pull request: yes

# What does this PR do?
#36963 #37281 #37306 causes regressions with training with deepspeed zero3, see our axolotl integration tests on the latest 4.51.0 release that includes these commits/PRs that all fail with zero3 https://github.com/axolotl-ai-cloud/axolotl/actions/runs/14286223137/job/40041643515

@LysandreJik [seems to agree that these deepspeed changes should be reverted](https://github.com/huggingface/transformers/pull/37281#issuecomment-2780872520)

/cc @stas00

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [ ] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#create-a-pull-request),
      Pull Request section?
- [ ] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [ ] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?


## Who can review?

@LysandreJik @SunMarc @zach-huggingface 
Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

<!-- Your PR will be replied to more quickly if you can figure out the right person to tag with @

 If you know how to use git blame, that is the easiest way, otherwise, here is a rough guide of **who to tag**.
 Please tag fewer than 3 people.

Models:

- text models: @ArthurZucker
- vision models: @amyeroberts, @qubvel
- speech models: @eustlb
- graph models: @clefourrier

Library:

- flax: @gante and @Rocketknight1
- generate: @zucchini-nlp (visual-language models) or @gante (all others)
- pipelines: @Rocketknight1
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @zach-huggingface and @SunMarc
- chat templates: @Rocketknight1

Integrations:

- deepspeed: HF Trainer/Accelerate: @SunMarc @zach-huggingface
- ray/raytune: @richardliaw, @amogkam
- Big Model Inference: @SunMarc
- quantization (bitsandbytes, autogpt): @SunMarc @MekkCyber

Documentation: @stevhliu

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @Rocketknight1
- PyTorch: See Models above and tag the person corresponding to the modality of the example.
- TensorFlow: @Rocketknight1

 -->


Comments:
Hi 👋, thank you for opening this pull request! The pull request is converted to draft by default. The CI will be paused while the PR is in draft mode. When it is ready for review, please click the `Ready for review` button (at the bottom of the PR page). This will assign reviewers and trigger CI.

Our multi-gpu integration CI is passing for Zero-3 with this branch

@winglian, I think you want to tag @Cyrilvallez and @ArthurZucker.

Does my proposal here helps?
https://github.com/huggingface/transformers/pull/37281#issuecomment-2779835748
It's incomplete but overcomes the earlier version's copying from meta device, as you can see in my comments - this is trying to help to channel all loading into the same code path. But Cyril said it's incomplete and more work is needed.

Also if you have resources could you please add the missing test to `tests/deepspeed/*` - to match your reported failure - because clearly your use case isn't being tested, and so the test suite is as good as its coverage.

Please be mindful of this gotcha https://github.com/huggingface/transformers/pull/37281#issuecomment-2779859617 - i.e. make sure the test model is a .safetensor type.

#37324 fixes this, We'll reopen a new PR with test cases for zero3