Remove recursive_approach_for_all_projects feature flag

What does this MR do and why?

The feature flag recursive_approach_for_all_projects was reintroduced and default-enabled in !64632 (merged) a year ago.

This MR is to remove the recursive_approach_for_all_projects feature flag.

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 #334817 (closed)