chore: turn OpenAIMixin into a pydantic.BaseModel (#3671)

# What does this PR do?

- implement get_api_key instead of relying on
LiteLLMOpenAIMixin.get_api_key
 - remove use of LiteLLMOpenAIMixin
 - add default initialize/shutdown methods to OpenAIMixin
 - remove __init__s to allow proper pydantic construction
- remove dead code from vllm adapter and associated / duplicate unit
tests
 - update vllm adapter to use openaimixin for model registration
 - remove ModelRegistryHelper from fireworks & together adapters
 - remove Inference from nvidia adapter
 - complete type hints on embedding_model_metadata
- allow extra fields on OpenAIMixin, for model_store, __provider_id__,
etc
 - new recordings for ollama
 - enhance the list models error handling
- update cerebras (remove cerebras-cloud-sdk) and anthropic (custom
model listing) inference adapters
 - parametrized test_inference_client_caching
- remove cerebras, databricks, fireworks, together from blanket mypy
exclude
 - removed unnecessary litellm deps

## Test Plan

ci

tests/unit/providers/inference/test_inference_client_caching.py

@@ -7,6 +7,8 @@
 import json
 from unittest.mock import MagicMock
 
+import pytest
+
 from llama_stack.core.request_headers import request_provider_data_context
 from llama_stack.providers.remote.inference.groq.config import GroqConfig
 from llama_stack.providers.remote.inference.groq.groq import GroqInferenceAdapter
@@ -18,72 +20,41 @@ from llama_stack.providers.remote.inference.together.config import TogetherImplC
 from llama_stack.providers.remote.inference.together.together import TogetherInferenceAdapter
 
 
-def test_groq_provider_openai_client_caching():
-    """Ensure the Groq provider does not cache api keys across client requests"""
-
-    config = GroqConfig()
-    inference_adapter = GroqInferenceAdapter(config)
-
-    inference_adapter.__provider_spec__ = MagicMock()
-    inference_adapter.__provider_spec__.provider_data_validator = (
-        "llama_stack.providers.remote.inference.groq.config.GroqProviderDataValidator"
-    )
-
-    for api_key in ["test1", "test2"]:
-        with request_provider_data_context(
-            {"x-llamastack-provider-data": json.dumps({inference_adapter.provider_data_api_key_field: api_key})}
-        ):
-            assert inference_adapter.client.api_key == api_key
-
-
-def test_openai_provider_openai_client_caching():
+@pytest.mark.parametrize(
+    "config_cls,adapter_cls,provider_data_validator",
+    [
+        (
+            GroqConfig,
+            GroqInferenceAdapter,
+            "llama_stack.providers.remote.inference.groq.config.GroqProviderDataValidator",
+        ),
+        (
+            OpenAIConfig,
+            OpenAIInferenceAdapter,
+            "llama_stack.providers.remote.inference.openai.config.OpenAIProviderDataValidator",
+        ),
+        (
+            TogetherImplConfig,
+            TogetherInferenceAdapter,
+            "llama_stack.providers.remote.inference.together.TogetherProviderDataValidator",
+        ),
+        (
+            LlamaCompatConfig,
+            LlamaCompatInferenceAdapter,
+            "llama_stack.providers.remote.inference.llama_openai_compat.config.LlamaProviderDataValidator",
+        ),
+    ],
+)
+def test_openai_provider_data_used(config_cls, adapter_cls, provider_data_validator: str):
     """Ensure the OpenAI provider does not cache api keys across client requests"""
 
-    config = OpenAIConfig()
-    inference_adapter = OpenAIInferenceAdapter(config)
+    inference_adapter = adapter_cls(config=config_cls())
 
     inference_adapter.__provider_spec__ = MagicMock()
-    inference_adapter.__provider_spec__.provider_data_validator = (
-        "llama_stack.providers.remote.inference.openai.config.OpenAIProviderDataValidator"
-    )
+    inference_adapter.__provider_spec__.provider_data_validator = provider_data_validator
 
     for api_key in ["test1", "test2"]:
         with request_provider_data_context(
             {"x-llamastack-provider-data": json.dumps({inference_adapter.provider_data_api_key_field: api_key})}
         ):
-            openai_client = inference_adapter.client
-            assert openai_client.api_key == api_key
-
-
-def test_together_provider_openai_client_caching():
-    """Ensure the Together provider does not cache api keys across client requests"""
-
-    config = TogetherImplConfig()
-    inference_adapter = TogetherInferenceAdapter(config)
-
-    inference_adapter.__provider_spec__ = MagicMock()
-    inference_adapter.__provider_spec__.provider_data_validator = (
-        "llama_stack.providers.remote.inference.together.TogetherProviderDataValidator"
-    )
-
-    for api_key in ["test1", "test2"]:
-        with request_provider_data_context({"x-llamastack-provider-data": json.dumps({"together_api_key": api_key})}):
-            together_client = inference_adapter._get_client()
-            assert together_client.client.api_key == api_key
-            openai_client = inference_adapter._get_openai_client()
-            assert openai_client.api_key == api_key
-
-
-def test_llama_compat_provider_openai_client_caching():
-    """Ensure the LlamaCompat provider does not cache api keys across client requests"""
-    config = LlamaCompatConfig()
-    inference_adapter = LlamaCompatInferenceAdapter(config)
-
-    inference_adapter.__provider_spec__ = MagicMock()
-    inference_adapter.__provider_spec__.provider_data_validator = (
-        "llama_stack.providers.remote.inference.llama_openai_compat.config.LlamaProviderDataValidator"
-    )
-
-    for api_key in ["test1", "test2"]:
-        with request_provider_data_context({"x-llamastack-provider-data": json.dumps({"llama_api_key": api_key})}):
             assert inference_adapter.client.api_key == api_key