Enable hk pages service

What does this MR do and why?

relate https://jihulab.com/gitlab-cn/gitlab/-/issues/4029

assumption both jihulab.com and hk saas are return true for following variable

::Gitlab.config.pages.access_control # show pages access control, however jh have different add logic to hide/show
::Gitlab.config.pages.enabled # enable pages service
::Gitlab::Pages.access_control_is_forced? # force access control, however jh have different logic
::Gitlab::CurrentSettings.current_application_settings.force_pages_access_control # # force access control, however jh have different logic

for jihulab.com

1. after SRE enable ff jh_pages for specific project or group, then pages service is enable
2. hide pages access level in project setting page, user cannot change it
3. project pages accessibility force set to private, only team member can access to it

for hk saas

1. after SRE enable ff jh_pages for specific project or group, then pages service is enable
2. project pages accessibility set to private by default
3. show pages access level in project setting page, user can change it