FIX(app): merge postgresql ExternalSecret

- Integrate vault/mas-postgres.yaml content into prod overlay
- Completely fix Kustomize external path reference issue

deploy/k8s/overlays/prod/externalsecret.yaml

@@ -23,20 +23,24 @@ spec:
 apiVersion: external-secrets.io/v1beta1
 kind: ExternalSecret
 metadata:
-  name: mas-postgres
+  name: postgresql-password
 spec:
   refreshInterval: 1h
   secretStoreRef:
     kind: ClusterSecretStore
     name: vault-backend
   target:
-    name: mas-postgres
+    name: postgresql-password
     creationPolicy: Owner
   data:
     - secretKey: password
       remoteRef:
-        key: mas/postgres
+        key: databases/postgresql
         property: PASSWORD
+    - secretKey: postgres-password
+      remoteRef:
+        key: databases/postgresql
+        property: POSTGRES_PASSWORD
 ---
 apiVersion: external-secrets.io/v1beta1
 kind: ExternalSecret