Update guidance and content regarding the previously planned removal of the Runner Registration Token in GitLab 18.0

Overview

Update all documentation and notices regarding the previously planned Runner Registration Token in GitLab 18.0

Background

After careful consideration, we have decided not to remove the Runner Registration Token capability from GitLab in the 18.0 release - May 2025. This applies to all GitLab.com and Self-Managed. On GitLab.com, the registration token option is disabled by default for new namespaces. We recommend that customers who still rely on the runner registration token method, discontinue the use of that method for registering new runners, and adopt the runner creation flow instead. The create flow that generates an authentication token is a more secure method for creating and managing runners.

https://docs.gitlab.com/security/tokens/#runner-authentication-tokens