[Bug]: ```test_base_url_valid_hosted_with_api_key``` fails for NVIDIA LLMs

### Bug Description

When running the tests under ```llama-index-integrations/llms/llama-index-llms-nvidia```, I got

```
FAILED tests/test_base_url.py::test_base_url_valid_hosted_with_api_key[https://integrate.api.nvidia.com/v1/] - AttributeError: 'NVIDIA' object has no attribute 'base_url'
```

### Version

I'm developing and contributing to LlamaIndex from source.

### Steps to Reproduce

I used the commands from the [quick start guide](https://github.com/run-llama/llama_index/blob/main/CONTRIBUTING.md#-quick-start-guide) to run the tests under ```llama-index-integrations/llms/llama-index-llms-nvidia```.

After cloning the repository and installing ```uv```:
```
uv sync
cd llama-index-integrations/llms/llama-index-llms-nvidia
uv run -- pytest
```

### Relevant Logs/Tracbacks

```shell
__________ test_base_url_valid_hosted_with_api_key[https://integrate.api.nvidia.com/v1/] ___________

base_url = 'https://integrate.api.nvidia.com/v1/'

    @pytest.mark.integration
    @pytest.mark.parametrize("base_url", ["https://integrate.api.nvidia.com/v1/"])
    def test_base_url_valid_hosted_with_api_key(base_url: str) -> None:
        llm = Interface()
>       assert llm.base_url == base_url

tests/test_base_url.py:56: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = NVIDIA(callback_manager=<llama_index.core.callbacks.base.CallbackManager object at 0x710153971c10>, system_prompt=None...ties=None, audio_config=None, context_window=3900, is_chat_model=True, is_function_calling_model=False, tokenizer=None)
item = 'base_url'

    def __getattr__(self, item: str) -> Any:
        private_attributes = object.__getattribute__(self, '__private_attributes__')
        if item in private_attributes:
            attribute = private_attributes[item]
            if hasattr(attribute, '__get__'):
                return attribute.__get__(self, type(self))  # type: ignore
    
            try:
                # Note: self.__pydantic_private__ cannot be None if self.__private_attributes__ has items
                return self.__pydantic_private__[item]  # type: ignore
            except KeyError as exc:
                raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}') from exc
        else:
            # `__pydantic_extra__` can fail to be set if the model is not yet fully initialized.
            # See `BaseModel.__repr_args__` for more details
            try:
                pydantic_extra = object.__getattribute__(self, '__pydantic_extra__')
            except AttributeError:
                pydantic_extra = None
    
            if pydantic_extra:
                try:
                    return pydantic_extra[item]
                except KeyError as exc:
                    raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}') from exc
            else:
                if hasattr(self.__class__, item):
                    return super().__getattribute__(item)  # Raises AttributeError if appropriate
                else:
                    # this is the current error
>                   raise AttributeError(f'{type(self).__name__!r} object has no attribute {item!r}')
E                   AttributeError: 'NVIDIA' object has no attribute 'base_url'

.venv/lib/python3.12/site-packages/pydantic/main.py:991: AttributeError
```

Labels: bug, triage
State: closed