fix: OpenAPI with provider get (#1627)

# What does this PR do?
- https://github.com/meta-llama/llama-stack/pull/1429 introduces
GetProviderResponse in OpenAPI, which is not needed, and not correctly
defined.

cc @cdoern 


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

## Test Plan
```
llama-stack-client providers list
```
<img width="610" alt="image"
src="https://github.com/user-attachments/assets/2f7b62a5-daf2-4bf9-9505-69755c7025fc"
/>


[//]: # (## Documentation)

llama_stack/apis/providers/providers.py

@@ -4,11 +4,10 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
-from typing import List, Protocol, runtime_checkable
+from typing import Any, Dict, List, Protocol, runtime_checkable
 
 from pydantic import BaseModel
 
-from llama_stack.distribution.datatypes import Provider
 from llama_stack.schema_utils import json_schema_type, webmethod
 
 
@@ -17,10 +16,7 @@ class ProviderInfo(BaseModel):
     api: str
     provider_id: str
     provider_type: str
-
-
-class GetProviderResponse(BaseModel):
-    data: Provider | None
+    config: Dict[str, Any]
 
 
 class ListProvidersResponse(BaseModel):
@@ -37,4 +33,4 @@ class Providers(Protocol):
     async def list_providers(self) -> ListProvidersResponse: ...
 
     @webmethod(route="/providers/{provider_id}", method="GET")
-    async def inspect_provider(self, provider_id: str) -> GetProviderResponse: ...
+    async def inspect_provider(self, provider_id: str) -> ProviderInfo: ...