custom timeout not used by function

[jhgoebbert]

Bug description

The default timeout for a process to become ready can now be set as timeout.

This can now be configured here with a default value of 5s

    timeout = Int(
        5, help="Timeout in seconds for the process to become ready, default 5s."
    ).tag(config=True)

https://github.com/jupyterhub/jupyter-server-proxy/blob/main/jupyter_server_proxy/config.py#L110

but it is not used here

    def get_timeout(self):
        """
        Return timeout (in s) to wait before giving up on process readiness
        """
        return 5

https://github.com/jupyterhub/jupyter-server-proxy/blob/main/jupyter_server_proxy/handlers.py#L918