Move the rest of pipeline header data to GraphQL

What does this MR do and why?

Small follow-up to !138183 (merged)

• Moves remainder of data to a SSO GraphQL
• Cleans up some mock data I noticed was not in-use

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

How to set up and validate locally

1. Visit a pipeline
2. Ensure the header section of the pipeline is working
3. Review code

Related to #434518 (closed)