Conversion Experiment Cleanup: expose free users to required merge request approvals

Summary

The experiment Conversion Experiment Rollout: expose free user... (#346176 - closed) is currently rolled out to 100% of users and has been deemed a success. The changes need to become an official part of the product.

Associated assets:

• Epic: &3695 (closed)
• Rollout issue: #346176 (closed)
• Experiment key / feature flag name: promote_mr_approvals_in_free

Steps

• Determine whether the feature should apply to SaaS and/or self-managed
  • SaaS only
• Determine whether the feature should apply to EE - and which tiers - and/or Core
  • Free SaaS only
• Determine if tracking should be kept as is, removed, or modified.
  • Tracking should be kept
• Ensure any relevant documentation has been updated.
  • No documentation needs to be updated
• Consider changes to any feature_category: introduced by the experiment if ownership is changing (PM for Growth and PM for the new category as DRIs)
  • No changes to any feature_category were introduced
• Check to see if the experiment introduced new design assets. Add them to the appropriate repos and document them if needed.
• Optional: Migrate experiment to a default enabled feature flag for one milestone and add a changelog. Converting to a feature flag can be skipped at the ICs discretion if risk is deemed low with consideration to both SaaS and (if applicable) self managed
• In the next milestone, remove the feature flag if applicable
• After the flag removal is deployed, clean up the feature/experiment feature flags by running chatops command in #production channel
• Ensure the corresponding Experiment Rollout issue is updated