Usage billing checks for GitLab Duo Agent Platform Self-Hosted

<!-- categories: Health & Connectivity -->

For GitLab Self-Managed customers using self-hosted models with an online license, the GitLab Duo Health now checks that the GitLab instance can reach the following endpoints:

• Customers Portal
• The AI Gateway
• Duo Workflow Service

Connection to these endpoints is necessary for usage billing.

Previously, if a firewall blocked any of these components, administrators had no indication of connectivity issues until users were unable to use a feature. Administrators can now use this new validation check to diagnose issues and review their firewall allowlist before any disruption to users.