Removing disk_free_limit from rabbitmq conf

disk_free_limit is set to mem_relative, which is a value relative
to memory. mem_relative is currently broken in rabbitmq 3.2.x.
http://rabbitmq.1065348.n5.nabble.com/disk-free-limit-mem-relative-1-0-td36187.html

There is no use for this config. This config was added due to legacy product.

Change-Id: I94ee009827b2d97a124e031824462426469d317f

cue/templates/install_rabbit.sh.tmpl

@@ -34,7 +34,6 @@ cat > /etc/rabbitmq/rabbitmq.config << EOF
   {rabbit, [{vm_memory_high_watermark, 0.4},
             {memory_alarms, true},
             {loopback_users,[]},
-            {disk_free_limit, {mem_relative, 1.0}},
             {cluster_partition_handling, pause_minority},
             {cluster_nodes, {[{%- for node_name in rabbit_nodes -%}
             'rabbit@{{node_name}}' {%- if not loop.last -%},{%- endif -%}