chore: turn OpenAIMixin into a pydantic.BaseModel

- 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

llama_stack/providers/remote/inference/databricks/databricks.py

@@ -9,7 +9,6 @@ from typing import Any
 from databricks.sdk import WorkspaceClient
 
 from llama_stack.apis.inference import (
-    Inference,
     Model,
     OpenAICompletion,
 )
@@ -22,31 +21,21 @@ from .config import DatabricksImplConfig
 logger = get_logger(name=__name__, category="inference::databricks")
 
 
-class DatabricksInferenceAdapter(
-    OpenAIMixin,
-    Inference,
-):
+class DatabricksInferenceAdapter(OpenAIMixin):
+    config: DatabricksImplConfig
+
     # source: https://docs.databricks.com/aws/en/machine-learning/foundation-model-apis/supported-models
     embedding_model_metadata = {
         "databricks-gte-large-en": {"embedding_dimension": 1024, "context_length": 8192},
         "databricks-bge-large-en": {"embedding_dimension": 1024, "context_length": 512},
     }
 
-    def __init__(self, config: DatabricksImplConfig) -> None:
-        self.config = config
-
     def get_api_key(self) -> str:
         return self.config.api_token.get_secret_value()
 
     def get_base_url(self) -> str:
         return f"{self.config.url}/serving-endpoints"
 
-    async def initialize(self) -> None:
-        return
-
-    async def shutdown(self) -> None:
-        pass
-
     async def openai_completion(
         self,
         model: str,