add subPath to volumeMount postgres-data

deploy/k8s/overlays/with-infra/postgres-statefulset.yaml

@@ -37,6 +37,7 @@ spec:
           volumeMounts:
             - name: postgres-data
               mountPath: /var/lib/postgresql/data
+              subPath: pgdata
           readinessProbe:
             exec:
               command: