Remove deploy-board illustration

What does this MR do and why?

Remove outdated deploy-board illustration. This illustration will be removed from the library. To avoid conflicts, I remove it from deprecated feature https://docs.gitlab.com/ee/user/project/deploy_boards.html

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

Before	After

How to set up and validate locally

Since the feature is deprecated, I can't find the way to reach this state

#474921 (closed)