Blueprint for gitlab-housekeeper automating repetitive developer tasks

What does this MR do and why?

This blueprint documents the philosophy behind the "GitLab Housekeeper" gem which was introduced in !139492 (merged) and has already been used to create many merge requests.

The tool should be used to save developers from mundane repetitive tasks that can be automated. The tool is scoped to any task where a developer needs to create a straightforward merge request and is known ahead of time.

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.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.