Add UI to allow disabling use of registration tokens for top-level groups

We need to expose the app and top namespace-level setting allow_runner_registration_token to the user, so that the admin/group owner can disable the use of registration tokens.

Proposal

• Designs in design management
• Figma file

1. Add a new setting on top-level groups to disable runner creation using registration tokens.
2. Update the existing setting text to incorporate that setting. 👇

New runner setting	What happens when this is not enabled

UI text changes

Runners

Runners are processes that pick up and execute CI/CD jobs for GitLab.

Runner registration creation

If both settings are disabled, new runners cannot be registered. Learn more.

• Project maintainers and group owners can create runners with registration tokens 👉 help text: When disabled, registration tokens will be disabled from runner pages, and maintainers and owners cannot use registration tokens to register runners. They can use authentication tokens instead as the more secure runner registration method.
• Maintainers of the all projects can register create runners
• Owners of the all groups can register create runners