Mailman: skip granting perms on the DB app users

At least until there's a better solution available (eg the Ansible bug
is fixed). For PG<9, there's no way to grant on all tables at once.

playbooks/groups/mailman.yml

@@ -92,13 +92,6 @@
 #        - hyperkitty
 #        - kittystore
 #        - postorius
-    - name: database users permissions
-      postgresql_user: name=${item}app db=$item
-                       priv=SELECT,INSERT,UPDATE,DELETE
-      with_items:
-        - hyperkitty
-        - kittystore
-        - postorius
 
 
 # Real MM/HK-specific work