[Bugfix] Fix call to init_logger in openai server

[NadavShmayo]

Currently when running the OpenAI entrypoint, all logs coming from this file will not be shown.
This is because the call to init_logger at the top of the file uses the __name__ global variable, and it's value is __main__ since this is the main file, which causes the init_logger function to return a logger with default configuration instead of the one configured in the logger file.

To solve this I changed the call to init_logger to pass a string instead of __name__, but another possible and potentially more elegant solution would be changing the init_logger function so the logger name is optional, and omitting it in the OpenAI entrypoint:

def init_logger(name: str = None) -> Logger:
    """The main purpose of this function is to ensure that loggers are
    retrieved in such a way that we can be sure the root vllm logger has
    already been configured."""

    return logging.getLogger(name or 'vllm')