Remove refactor_code_quality_extension Feature Flag

What does this MR do and why?

This MR removes the refactor_code_quality_extension Feature Flag

Rollout Issue: #363845 (closed)

Screenshots or screen recordings

no visual changes

How to set up and validate locally

Recreate the Codequality MR Widget and see if it still works as expected.

To recreate:

1. clone https://gitlab.com/jannik_lehmann/code-quality-test
2. recreate: jannik_lehmann/code-quality-test!3 (closed) locally
3. see codequality MR widget in action

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.