Fix docker-compose installs

In a series of unfortunate events, my patch yesterday didnt actually work. This fixes that.

installer/roles/local_docker/templates/credentials.py.j2

@@ -12,9 +12,10 @@ DATABASES = {
 BROKER_URL = 'amqp://{}:{}@{}:{}/{}'.format(
     "{{ rabbitmq_user }}",
     "{{ rabbitmq_password }}",
-    "localhost",
+    "rabbitmq",
     "5672",
     "awx")
+
 CHANNEL_LAYERS = {
     'default': {'BACKEND': 'asgi_amqp.AMQPChannelLayer',
                 'ROUTING': 'awx.main.routing.channel_routing',