chore(kube-prometheus): Migrate to ArgoCD App of Applications

Move the ArgoCD Application resource definition to follow the ArgoCD App
of Applications pattern.

Author: ssoriche

platform/kube-prometheus/do/application.yaml renamed to argocd-applications/do/kube-prometheus.yaml

@@ -4,6 +4,5 @@ kind: Kustomization
 resources:
   - ../base/
   - ./ingress.yaml
-  - ./application.yaml
   - ./sealedsecret-thanos-objectstorage.yaml
   - ./sealedsecret-grafana-config.yaml