chore: convert prometheus config to kustomize component

Convert config/prometheus/ from a regular kustomization to a kustomize
Component so it can be included via the Flux Kustomization components
list in the infra repo.

Author: scotwells

config/prometheus/kustomization.yaml

@@ -1,2 +1,4 @@
+apiVersion: kustomize.config.k8s.io/v1alpha1
+kind: Component
 resources:
-- monitor.yaml
+  - monitor.yaml