Remove review-apps documentation from gitlab-org/gitlab

Context

Part of Epic &19358 - Deprecate/Remove review-apps for gitlab-org/gitlab.

Review-apps infrastructure and code are being removed. We need to identify and remove or update any documentation that references review-apps in the gitlab-org/gitlab repository.

Tasks

• Search for review-apps references in doc/ directory
• Search for review-apps references in README files
• Search for review-apps references in code comments
• Remove or update documentation as appropriate
• Update any developer guides that mention review-apps
• Verify no broken documentation links remain

Search Suggestions

# Search for review-apps in documentation
grep -r "review-apps\|review apps" doc/
grep -r "review-apps\|review apps" *.md

Related

• Epic: &19358
• Code removal issue: (will be linked after creation)