Turn off authentication to work with authentication proxies

## What?
Turn off graylog authentication

## Why?
We would like to place graylog to kubernetes with proxies which already make authentication with our IDP and they can pass to graylog whatever headers they would need for graylog authorization to work

## Your Environment

* Graylog Version:
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: