WIP: Migrate the contents of `k8s-workloads/monitoring` to helmfile and `gitlab-helmfiles`

This is for https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/9572

This migration converts everything into four distinct helm releases

• gitlab-monitoring-secrets which encapuslates the secrets needed for prometheus IAP + SSL
• gitlab-monitoring which is identical to what is there currently
• thanos-query which encapsulates the simple thanos-query deployment and service
• cloudflare-exporter which encapsulates the cloudflare-exporter deployment and secret