Refactor: simplify ModelHTTPError handling

- Align with other model implementations (openai, groq) by removing unnecessary error transformation logic

Resolves: #3088

Author: timothy-jeong

pydantic_ai_slim/pydantic_ai/models/google.py

@@ -396,7 +396,7 @@ async def _generate_content(
         func = self.client.aio.models.generate_content_stream if stream else self.client.aio.models.generate_content
         try:
             return await func(model=self._model_name, contents=contents, config=config)  # type: ignore
-        except errors.APIError as e:  # pragma: no cover
+        except errors.APIError as e:
             if (status_code := e.code) >= 400:        
                 raise ModelHTTPError(status_code=status_code, model_name=self._model_name, body=e.details) from e
             raise # pragma: lax no cover