change schema -> dataset_schema (#442)

# What does this PR do?

- `schema` should not a field w/ pydantic warnings
- change `schema` to `dataset_schema`

<img width="855" alt="image"
src="https://github.com/user-attachments/assets/47cb6bb9-4be0-46a5-8701-24d24e2eaabd">


## Test Plan

```
pytest -v -s -m meta_reference_eval_together_inference_huggingface_datasetio eval/test_eval.py
```


## Before submitting

- [ ] This PR fixes a typo or improves the docs (you can dismiss the
other checks if that's the case).
- [ ] Ran pre-commit to handle lint / formatting issues.
- [ ] Read the [contributor
guideline](https://github.com/meta-llama/llama-stack/blob/main/CONTRIBUTING.md),
      Pull Request section?
- [ ] Updated relevant documentation.
- [ ] Wrote necessary unit or integration tests.

llama_stack/distribution/routers/routing_tables.py

@@ -332,7 +332,7 @@ class DatasetsRoutingTable(CommonRoutingTableImpl, Datasets):
             identifier=dataset_id,
             provider_resource_id=provider_dataset_id,
             provider_id=provider_id,
-            schema=schema,
+            dataset_schema=schema,
             url=url,
             metadata=metadata,
         )