Set ulimit from /etc/default/rabbitmq-server

Allow rabbitmq to handle a lot of connections on scale

Change-Id: Ia63e9eae2344535a2b0213c0fb2e9693c6317735
Closes-Bug: 1405657
Signed-off-by: Sergii Golovatiuk <sgolovatiuk@mirantis.com>
Merge "Set ulimit from /etc/default/rabbitmq-server"