Merge branch '376954-openapiv2-pages' into 'master'

Add PagesDomains to OpenAPI docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/107950



Merged-by: Roy Zwambag <rzwambag@gitlab.com>
Approved-by: Matt Kasa <mkasa@gitlab.com>
Approved-by: Roy Zwambag <rzwambag@gitlab.com>
Co-authored-by: David O'Regan <doregan@gitlab.com>