Move level visibility for groups to common area

What does this MR do?

• Moves previously registration/groups only code to a shared area for reuse during #292058

Note

1. Developer only facing changes, so no changelog.

2. In order to see these changes locally, enable the onboarding_issues experiment in the console by running:

   Feature.enable_percentage_of_time(:onboarding_issues_experiment_percentage, 100)

Sign in and visit: http://localhost:3000/users/sign_up/groups/new

Screenshots (strongly suggested)

What the code being moved supplies

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #292058