* upstream/master: (64 commits)
  Merge branch 'open-redirect-fix-continue-to' into 'security'
  Merge branch 'open-redirect-host-fix' into 'security'
  Merge branch 'path-disclosure-proj-import-export' into 'security'
  Merge branch '29364-private-projects-mr-fix'
  Merge branch '30125-markdown-security'
  Issue title realtime
  Update CHANGELOG.md for 8.16.9
  Update CHANGELOG.md for 8.17.5
  Update CHANGELOG.md for 9.0.4
  Add "search" optional param and docs for V4
  Use PDFLab to render PDFs in GitLab
  Separate Scala from Java in CI examples
  Fix broken link
  Reorganize CI examples, add more links
  Refactor CI index page
  Remove deprecated field from workhorse response
  Use gitlab-workhorse 1.4.3
  Document how ETag caching middleware handles query parameters
  Make group skip validation in the frontend
  Use NamespaceValidator::WILDCARD_ROUTES in ETag caching middleware
  ...