Refactor EE request specs for issue lists

What does this MR do and why?

MR 5/5 to add full coverage on the new root level issues query. Everything that was tested at the project level is now also tested at the root level by using a shared example. This MR takes care of the last part, EE specs. Also discovered an N+1 query that was also fixed.

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.

Related to #377514 (closed)