chore(postgresql-cluster): remove 1c2g plan

Author: EamonZhang

addons/postgresql-cluster/15/chart/postgresql-cluster/values.yaml

@@ -356,7 +356,7 @@ persistentVolume:
   ##   set, choosing the default provisioner.  (gp2 on AWS, standard on
   ##   GKE, AWS & OpenStack)
   ##
-  # storageClass: "-"
+  storageClass: ""
   subPath: ""
   mountPath: "/home/postgres/pgdata"
   annotations: {}