Use canary nodes for Kubernetes deployments

Our approach to canary deployments for kubernetes is to route at HAProxy based on the request path, to direct a request to a canary namespace. This is a bit different than GitLab canary deployments which uses Kubernetes canary deploy that deploys to a subset of pods before the others. This also integrates with GitLab deploy boards with a yellow annotations:

To use the canary feature, the Delivery team will need to use the same type of canary deployments that may happen by adopting the auto-deploy AutoDevops wrappers https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image/blob/master/src/bin/auto-deploy or the CI jobs https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/ci/templates/Jobs/Deploy.gitlab-ci.yml