Refactor project policy ownership logic

What does this MR do and why?

Tiny refactor in the quest to tidy up owner logic for projects!

See &7405 (comment 862600338) for a breakdown of owner logic and direction.

Feature flag faster_owner_access can be toggled to test speed and DB activity 👍

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 #362329 (closed) and #21432 (closed)

FF Rollout issue: #362328 (closed)