🚨[wav2vec2] Support attn_implementation=sdpa dispatch
Author: YangKai0616
Pull request: yes

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# What does this PR do?

The wav2vec2_conformer/bert and SeamlessM4T/v2 models fail during the initialization phase when using `from_pretrained(..., attn_implementation="sdpa")`. This PR enables standard `attn_implementation="sdpa"` dispatch to these models.

Comments:
Hi @ArthurZucker @vasqu , pls help review, thx!

Hey @vasqu , I've addressed all the comments and completed the changes. Please review again. Thanks!
Additionally, the current `run_slow` results remain consistent with `upstream/main`. Some known failing cases will not be fixed in this PR for now.

View the CircleCI Test Summary for this PR:

https://huggingface.co/spaces/transformers-community/circle-ci-viz?pr=46196&sha=9ac3ec

@vasqu I just realized you meant refactoring the root `wav2vec2` model—sorry for the confusion!😀

I've completed the refactor and updated the related models as well. 

On my local A100 machine, all tested models show the same performance as the main branch. Could you please take another look? Thank you!

The CI failure is unrelated to this PR and passes in my local testing.

Thanks a lot! @YangKai0616 I will review this a bit later (sometime this week) because it will take a lot of time (but worth it)

Need to allocate some proper time for this :hugs: don't hesitate to ping me at the end of the week if I forgot to review!

Hey @vasqu , the conflicts have been resolved. Please review again, thanks!

Hey @vasqu , CI errors appear unrelated to this PR, could you please take another look? Thanks!

Will try as soon as I can, sorry I know i've been letting this PR slide :cry: 

Thank you for your contribution 🤗!

## CI Security Gate — automatic approval blocked

This PR was **not** automatically approved for CI because the security gate failed.

**Possible reasons:**
- The PR touches 50 or more files — only PRs with fewer than 50 changed files are automatically approved
- A changed file is outside the allowed directories (`src/`, `tests/`, `docs/`, `utils/`), has a disallowed extension (only `.py`, `.txt`, `.md` permitted outside `tests/` and `docs/`), or is not `.md`/`.yml` inside `docs/`
- A new high-severity security issue was detected in the changed Python files (Bandit check)

See the [workflow run](https://github.com/huggingface/transformers/actions/runs/28912395352) for the exact violations.

A maintainer can review and manually approve CI if a finding is a false positive.

**[For maintainers]** Suggested jobs to run (before merge)

run-slow: data2vec, hubert, patchtsmixer, patchtst, seamless_m4t, seamless_m4t_v2, sew, sew_d, unispeech, unispeech_sat, wav2vec2, wav2vec2_bert, wav2vec2_conformer, wavlm

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### CI recap

**Dashboard:** [View test results in Grafana](https://transformers-ci.lor-e.huggingface.cool/d/pytest-observability-by-pr/pytest-observability-branch?var-pr=46196)
**Latest run:** [29299479341:2](https://github.com/huggingface/transformers/actions/runs/29299479341)
**Result:** `failure` | **Jobs:** 15 | **Tests:** 160,937 | **Failures:** 3 | **Duration:** 15h 26m

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The CI failures seem unrelated to this PR.
Friendly ping @vasqu .


Yup aware of it, currently no bandwidth but I have it on my backlog. Super sorry @YangKai0616