[mailman3] Use production FAS for staging mailman deployment

Previous staging deployment used production FAS instance for authentication and
it seems to make new accounts when pointing to staging FAS. Let's redirect that
and see if the accounts will be correctly loaded.

Signed-off-by: Michal Konecny <mkonecny@redhat.com>

playbooks/groups/mailman.yml

@@ -109,9 +109,9 @@
     mailman_hyperkitty_db_pass: "{{ mailman_hk_db_pass }}"
     mailman_hyperkitty_cookie_key: "{{ mailman_hk_cookie_key }}"
     mailman_hyperkitty_archiver_key: "{{ mailman_hk_stg_archiver_key }}"
-    mailman_openidc_server_url: https://id.stg.fedoraproject.org/openidc
     mailman_openidc_secret: "{{ mailman_stg_oidc_pass }}"
     mailman_httpd_hostname: lists.stg.fedoraproject.org
+    mailman_openidc_client_id: "mailman3{{ env_suffix }}"
     when: env == "staging"
   - {role: fedmsg/base,
      when: env != "staging"}