bodhi: use passive declares in fedora-messaging

AMQP clients don't have permission to create objects, so they can only
validate the objects exist with passive declarations.

roles/bodhi2/base/templates/fedora-messaging.toml.j2

@@ -7,7 +7,7 @@ topic_prefix = "org.fedoraproject.prod"
 {% endif %}
 
 publish_exchange = "amq.topic"
-passive_declares = false
+passive_declares = true
 
 {# If bodhi_message_routing_keys is defined, this must be a consumer so let's also set up the consumer
    config. #}