test: revamp eval related integration tests (#1433)

# What does this PR do?
- revamp and clean up datasets/scoring/eval integration tests
- closes https://github.com/meta-llama/llama-stack/issues/1396

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
**dataset**
```
LLAMA_STACK_BASE_URL=http://localhost:8321 pytest -v tests/integration/datasetio/
```
<img width="842" alt="image"
src="https://github.com/user-attachments/assets/88fc2b6a-b496-47bf-bc0c-8fea48ba36ff"
/>

**scoring**
```
LLAMA_STACK_CONFIG=fireworks pytest -v tests/integration/scoring --text-model meta-llama/Llama-3.1-8B-Instruct --judge-model meta-llama/Llama-3.1-8B-Instruct
```
<img width="851" alt="image"
src="https://github.com/user-attachments/assets/50f46415-b44c-4c37-a6c3-076f2767adb3"
/>


**eval**
```
LLAMA_STACK_CONFIG=fireworks pytest -v tests/integration/eval --text-model meta-llama/Llama-3.1-8B-Instruct --judge-model meta-llama/Llama-3.1-8B-Instruct
```
<img width="841" alt="image"
src="https://github.com/user-attachments/assets/8eb1c65c-3b39-4d66-8ff4-f471ca783e49"
/>


[//]: # (## Documentation)

tests/integration/datasetio/test_datasetio.py

@@ -9,13 +9,9 @@ import mimetypes
 import os
 from pathlib import Path
 
-import pytest
-
 # How to run this test:
 #
-# pytest llama_stack/providers/tests/datasetio/test_datasetio.py
-#   -m "meta_reference"
-#   -v -s --tb=short --disable-warnings
+# LLAMA_STACK_CONFIG="template-name" pytest -v tests/integration/datasetio
 
 
 def data_url_from_file(file_path: str) -> str:
@@ -60,42 +56,29 @@ def register_dataset(llama_stack_client, for_generation=False, for_rag=False, da
             "generated_answer": {"type": "string"},
         }
 
+    dataset_providers = [x for x in llama_stack_client.providers.list() if x.api == "datasetio"]
+    dataset_provider_id = dataset_providers[0].provider_id
+
     llama_stack_client.datasets.register(
         dataset_id=dataset_id,
         dataset_schema=dataset_schema,
         url=dict(uri=test_url),
-        provider_id="localfs",
+        provider_id=dataset_provider_id,
     )
 
 
-def test_datasets_list(llama_stack_client):
-    # NOTE: this needs you to ensure that you are starting from a clean state
-    # but so far we don't have an unregister API unfortunately, so be careful
-
-    response = llama_stack_client.datasets.list()
-    assert isinstance(response, list)
-    assert len(response) == 0
-
-
-def test_register_dataset(llama_stack_client):
+def test_register_unregister_dataset(llama_stack_client):
     register_dataset(llama_stack_client)
     response = llama_stack_client.datasets.list()
     assert isinstance(response, list)
     assert len(response) == 1
     assert response[0].identifier == "test_dataset"
 
-    with pytest.raises(ValueError):
-        # unregister a dataset that does not exist
-        llama_stack_client.datasets.unregister("test_dataset2")
-
     llama_stack_client.datasets.unregister("test_dataset")
     response = llama_stack_client.datasets.list()
     assert isinstance(response, list)
     assert len(response) == 0
 
-    with pytest.raises(ValueError):
-        llama_stack_client.datasets.unregister("test_dataset")
-
 
 def test_get_rows_paginated(llama_stack_client):
     register_dataset(llama_stack_client)