Fix Hunyuan-VL PIL image resize parity with reference preprocessing
Author: IMvision12
Pull request: yes

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This PR removes the manual PIL resize workaround from the Hunyuan-VL PIL image processor and routes resizing through the shared processor backend.

The previous code manually converted numpy images to PIL, called `PIL.Image.resize(...)`, then converted back to numpy because the shared resize path produced degraded results. The difference came from the default resize method: plain PIL resize matches bicubic behavior here, while the shared path was falling back to bilinear when `resample=None`.

This PR preserves the original HunyuanOCR preprocessing behavior by defaulting Hunyuan-VL PIL resize to `PILImageResampling.BICUBIC` when no `resample` value is provided.

### Tests

- Added a regression test confirming the default Hunyuan-VL PIL resize output matches explicit bicubic resize.
- Verified that bilinear produces different output, preventing accidental regression.

Comments:
cc @zucchini-nlp

run-slow: hunyuan_vl

[Workflow Run ⚙️](https://github.com/huggingface/transformers/actions/runs/29498708863)

This comment contains `run-slow`, running the specified jobs: 

models: ["models/hunyuan_vl"]
quantizations: []

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_47233). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

## CI Results
[Workflow Run ⚙️](https://github.com/huggingface/transformers/actions/runs/29498708863)

### Commit Info
| Context | Commit | Description |
|---------|--------|-------------|
| RUN | [27e9fbe5](https://github.com/huggingface/transformers/commit/27e9fbe593fca9cdd4ddf4dacb186c5e967abc06) | workflow commit (merge commit) |
| PR | [331b795a](https://github.com/IMvision12/transformers/commit/331b795a0b170434845ba242e08c550f0be0a757) | branch commit (from PR) |
| main | [a8609bed](https://github.com/huggingface/transformers/commit/a8609bed2ad1593e7d756006525a10053d4d5bc6) | base commit (on `main`) |

⚠️ **Model CI failed to report results**

The test failure analysis could not be completed. Please check the [workflow run](https://github.com/huggingface/transformers/actions/runs/29498708863) for details.


Oh right, slow tests are failing in main as well, though the error messages look different. Can you check locally @IMvision12 ?

@zucchini-nlp Yeah, I checked locally on GPU and the same slow Hunyuan-VL test fails because the generated text snapshot changed after the PIL image preprocessing update. I updated the expected `("cuda", None)` output for `test_small_model_integration_test_multi_image_nested` using the CI-generated text.

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/29522034685) 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: hunyuan_vl

@zucchini-nlp can you again run the slow test?

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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=47233)
**Latest run:** [29068900477:2](https://github.com/huggingface/transformers/actions/runs/29575841034)
**Result:** `success` | **Jobs:** 3 | **Tests:** 49 | **Failures:** 0 | **Duration:** 1m 49s

<!-- ci-dashboard-recap:end -->

run-slow: hunyuan_vl

[Workflow Run ⚙️](https://github.com/huggingface/transformers/actions/runs/29576424869)

This comment contains `run-slow`, running the specified jobs: 

models: ["models/hunyuan_vl"]
quantizations: []

## CI Results
[Workflow Run ⚙️](https://github.com/huggingface/transformers/actions/runs/29576424869)

### Commit Info
| Context | Commit | Description |
|---------|--------|-------------|
| RUN | [1665004c](https://github.com/huggingface/transformers/commit/1665004c747cf320795bde5fe162be1cdf612172) | workflow commit (merge commit) |
| PR | [de21dc48](https://github.com/IMvision12/transformers/commit/de21dc4801a0bb317c83fa40bbd0dee550d2f7e4) | branch commit (from PR) |
| main | [75a5542e](https://github.com/huggingface/transformers/commit/75a5542ef0a626f1ea9d8a67d4c7dcfd98fdd3a5) | base commit (on `main`) |

✅ No failing test specific to this PR 🎉 👏 !