Stop publishing subunit worker data to mqtt

We are going to cleanup firehose.openstack.org as it never really ended
up being used for significant things and we would need to rewrite the
puppet into ansible at this point. Before we cleanup the server ensure
that things are not talking to it.

The only thing I can find that externally talks to it is the subunit
workers. germqtt and lpmqtt run on firehose so will be cleaned out when
firehose goes away.

Change-Id: I5b657aad1a276a18e58d09f5b2108940d0bd8ac2

modules/openstack_project/templates/logstash/jenkins-subunit-worker.yaml.erb

@@ -1,9 +1,9 @@
 gearman-host: logstash.openstack.org
 gearman-port: 4730
 config: /etc/subunit2sql/subunit2sql.conf
-mqtt-host: firehose.openstack.org
-mqtt-port: 8883
-mqtt-topic: gearman-subunit/<%= @hostname %>
-mqtt-user: <%= @mqtt_user %>
-mqtt-pass: <%= @mqtt_pass %>
-mqtt-ca-certs: /etc/subunit2sql/mqtt-root-CA.pem.crt
+#mqtt-host: firehose.openstack.org
+#mqtt-port: 8883
+#mqtt-topic: gearman-subunit/<%= @hostname %>
+#mqtt-user: <%= @mqtt_user %>
+#mqtt-pass: <%= @mqtt_pass %>
+#mqtt-ca-certs: /etc/subunit2sql/mqtt-root-CA.pem.crt