Fix: gitlab duo tab shows up in usage quota page

What does this MR do and why?

• Fix issue #4547 (closed)
• Remove the code_suggestion feature in the premium_feature list so that the method for License.feature_available?(:code_suggestion) will return false to disable the GitLab Duo feature.

Fix: gitlab duo tab shows up in usage quota page

• Remove the code_suggestion feature in GITLAB_PREMIUM_FEATURES list

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. Boot up GDK with GITLAB_SIMULATE_SAAS=true
2. Navigate to any Group > Settings > Usage Quota
3. Observe.