fix: resolve integration test failures by migrating COCO image loading to HF Hub fixtures
Author: abhishekkapoorx
Pull request: yes

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# What does this PR do?

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This PR resolves the integration test failures triaged in #47205. 

The domain `images.cocodataset.org` has been unstable, resulting in connection timeouts and failing integration tests across multiple model pipelines. To address this, we have migrated COCO-dataset image loading in our test suites to use the mirrored fixtures on the Hugging Face Hub under `hf-internal-testing/fixtures-coco` and utilizing local path redirection.

### Key Changes:
1. **Added test helper**: Introduced `load_test_image` in `tests/test_processing_common.py` which wraps `load_image` and automatically processes remote URLs with `url_to_local_path`.
2. **Refactored tests**: Converted occurrences of direct `requests.get` or `httpx.get` targeting `http://images.cocodataset.org/val2017/000000039769.jpg` to the new `load_test_image` helper pointing to the Hugging Face mirror.
3. **Cleaned up CI downloads**: Removed direct references to stale `images.cocodataset.org` URLs from the `URLS_FOR_TESTING_DATA` registry in `utils/fetch_hub_objects_for_ci.py`.

This prevents flaky network issues and leverages local caching during CI execution.

## Related Issues
Fixes #47205

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Models:

- text models: @ArthurZucker @Cyrilvallez @vasqu
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- audio models: @eustlb @ebezzam @vasqu
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Comments:
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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=47219)
**Latest run:** [29143766271:2](https://github.com/huggingface/transformers/actions/runs/29143766271)
**Result:** `failure` | **Jobs:** 2 | **Tests:** 21 | **Failures:** 1 | **Duration:** 2m 18s

> **Code quality check failed**: test jobs were skipped. Fix the code quality issues and push again to run tests.

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

run-slow: aimv2, aria, deepseek_vl_hybrid, eomt, eomt_dinov3, fast_vlm, flava, fuyu, idefics, imagegpt, kimi_k25, layoutlmv2, lfm2_vl, llava, minimax_m3_vl, pix2struct

@ydshieh In [src/transformers/modeling_utils.py](https://github.com/huggingface/transformers/blob/main/src/transformers/modeling_utils.py), we are using the `axis` but latest documentation of torch uses `dim`. I think we should fix this as well.
```diff --git a/src/transformers/modeling_utils.py b/src/transformers/modeling_utils.py
index 3f14d74979..f27ae1d884 100644
--- a/src/transformers/modeling_utils.py
+++ b/src/transformers/modeling_utils.py
@@ -982,7 +982,7 @@ class ModuleUtilsMixin:
                     torch.ones((batch_size, seq_length, prefix_seq_len), device=device, dtype=causal_mask.dtype),
                     causal_mask,
                 ],
-                axis=-1,
+                dim=-1,
             )
 
         extended_attention_mask = causal_mask[:, None, :, :] * attention_mask[:, None, None, :]
```

This is causing local typing check to fail.

run-slow: aimv2, aria, deepseek_vl_hybrid, eomt, eomt_dinov3, fast_vlm, flava, fuyu, idefics, imagegpt, kimi_k25, layoutlmv2, lfm2_vl, llava, minimax_m3_vl, pix2struct

[Workflow Run ⚙️](https://github.com/huggingface/transformers/actions/runs/29144843550)

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

models: ["models/aimv2", "models/aria", "models/deepseek_vl_hybrid", "models/eomt", "models/eomt_dinov3", "models/fast_vlm", "models/flava", "models/fuyu", "models/idefics", "models/imagegpt", "models/kimi_k25", "models/layoutlmv2", "models/lfm2_vl", "models/llava", "models/minimax_m3_vl", "models/pix2struct"]
quantizations: []

Sorry I just realized that work was started earlier at https://github.com/huggingface/transformers/pull/47218 
I messed up when I did the triaging, sorry about that

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_47219). 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/29144843550)

### Commit Info
| Context | Commit | Description |
|---------|--------|-------------|
| RUN | [61e10d08](https://github.com/huggingface/transformers/commit/61e10d081b443266314edb192e86c3785dbcb2dc) | workflow commit (merge commit) |
| PR | [041d01ac](https://github.com/abhishekkapoorx/transformers/commit/041d01acae77fdaa95d7a9e6c56b2b8c8e3e52bd) | branch commit (from PR) |
| main | [1f8daee0](https://github.com/huggingface/transformers/commit/1f8daee0c80cd53a44b1094b79309dd8675d6392) | base commit (on `main`) |

✅ No failing test specific to this PR 🎉 👏 !