Add ai-assisted to k8s cny stage
Context
In https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24005 we created a new service that is running the GitLab-rails webservice for serving AI-related requests coming from other clients (VSCode).
Problem
In gitlab-com/gl-infra/k8s-workloads/gitlab-com!2970 (comment 1517226606) we noticed that the service does not have a cny stage and that the config is duplicated for each zonal cluster.
Proposed Solution
To avoid duplication of the various configurations, create a cny stage.
Edited by Michele Bursi