Revert using local keycloak to central keycloak.

infra/nomad.yaml

 keycloak:
-  server_url: 'http://keycloak:8080/'
+  server_url: 'https://nomad-lab.eu/fairdi/keycloak/auth/'
   realm_name: 'fairdi_nomad_test'
-  public_server_url: 'http://localhost:8080/'
 services:
   admin_user_id: 'c97facc2-92ec-4fa6-80cf-a08ed957255b'
 client: