Make Kafka listen on all interfaces

It seems that even if host.name is configured with IPv4,
Kafka still listens on IPv6 (if available). As a consequence
in some scenarios (https://review.openstack.org/#/c/409144/
Patch-Set 13) some services are unable to connect to Kafka.

Change-Id: I12be88eac41edefde8b3936f4a92de4f636907d9

devstack/files/kafka/server.properties

@@ -26,7 +26,7 @@ broker.id=0
 port=9092
 
 # Hostname the broker will bind to. If not set, the server will bind to all interfaces
-host.name=127.0.0.1
+#host.name=127.0.0.1
 
 # Hostname the broker will advertise to producers and consumers. If not set, it uses the
 # value for "host.name" if configured.  Otherwise, it will use the value returned from

devstack/plugin.sh

@@ -456,10 +456,6 @@ function install_kafka {
 
     sudo chmod 644 /etc/kafka/server.properties
 
-    if [[ ${SERVICE_HOST} ]]; then
-        sudo sed -i "s/host\.name=127\.0\.0\.1/host.name=${SERVICE_HOST}/g" /etc/kafka/server.properties
-    fi
-
     sudo systemctl enable kafka
 
     sudo systemctl start kafka || sudo systemctl restart kafka