Sync feature category manifest

What does this MR do and why?

For gitlab-com/gl-infra/scalability#1496 (closed)

This MR is to sync the feature categories from Handbook's stages.yml to config/feature_categories.yml manifest file. There are two sets of changes this time:

• Consolidating Testing Categories (gitlab-com/www-gitlab-com!95994 (merged)):
  • accessability_testing is merged to code_testing
  • usability_testing is merged to review_apps
• New runner categories (gitlab-com/www-gitlab-com!90885 (merged))

Screenshots or screen recordings

No, this MR doesn't introduce any user-facing changes.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.