Removing Duo auto assign reference from docs

What does this MR do and why?

Removing this section from the docs, given it is currently behind a feature flag and not yet customer facing. Plans to make this available to customers are currently on hold pending a full UX review of AI settings. See this thread for details.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.