Add Lock project membership to group to registration features

What does this MR do and why?

We want to add Lock project membership to group to features available to users who have service ping data sharing enabled.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Testing previous behavior:
   • Make sure you're on a Premium/Ultimate plan GitLab GDK instance
   • Select some group
   • Select Settings -> General in Group sidebar
   • Expand the Permissions and group features section
   • Verify you can see Users cannot be added to projects in this group checkbox under Membership section.
   • Under Membership, select Users cannot be added to projects in this group
   • Save changes.
   • Select some project from this group and select Manage -> Members in Project sidebar.
   • Verify you don't see Invite members button anymore.
2. When registration features are enabled:
   • Make sure you're on a free plan GitLab GDK instance (for example, remove current license or stub #current to return nil)
   • Make sure you have the Registration Features checkbox enabled (Admin -> Settings -> Metrics and profiling -> Usage statistics -> Enable Service Ping & Enable Registration Features)
   • Select some group
   • Select Settings -> General in Group sidebar
   • Expand the Permissions and group features section
   • Verify you can see Users cannot be added to projects in this group checkbox under Membership section.
3. When registration features are disabled:
   • Make sure you're on a free plan GitLab GDK instance
   • Make sure you have the registration features checkbox disabled (Admin -> Settings -> Metrics and profiling -> Usage statistics -> Enable Registration Features)
   • Select some group
   • Select Settings -> General in Group sidebar
   • Expand the Permissions and group features section
   • Verify you don't see Users cannot be added to projects in this group checkbox under Membership section.
4. Make sure that the new text appears on the docs page:
   • run gdk restart gitlab-docs
   • go to <local_gitlab_docs_host>/ee/user/admin_area/settings/usage_statistics.html#registration-features-program and make sure the new section is on the page and the link works

Updated doc	Link page

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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

Related to #422272 (closed)