## Feature Flag for Multiple Default Models in AI Gateway ### Description Implement a feature flag mechanism to control the selection of default models when multiple options are available in the AI Gateway/Duo Workflow Service. ### Requirements 1. **GitLab Rails Integration** - Add a new feature flag in gitlab-rails to control default model selection behavior 2. **Header Forwarding** - Forward the feature flag value as a header in requests from GitLab Rails to the AI Gateway/Duo Workflow Service 3. **AI Gateway/Duo Workflow Service Logic** - When multiple `default_models` options are configured: - If the feature flag header is not present or set to `false`: use only the first default model option - If the feature flag header is set to `true`: allow selection from all available default model options *** _Description was generated using AI_