fix(postgres): Add missing lines to previous commit…

This patch fulfils the previous's promises and puts the right port
string in place. 

infrastructure/postgres/user-namespace-network-policy.yaml

@@ -21,11 +21,11 @@ spec:
                 matchLabels:
                   name: zalando-postgres
             ports:
-            - containerPort: 8008
+            - port: 8008
               protocol: TCP
-            - containerPort: 5432
+            - port: 5432
               protocol: TCP
-            - containerPort: 8080
+            - port: 8080
               protocol: TCP
           podSelector:
             matchLabels: