To install RabbitMQ and set the installation location to something other than the default (/var/lib/rabbit) set the variable RABBITMQ_DB_DIR to the desired directory in the site_vars file. This installs RabbitMQ in the specified location.
The only way to change the installation location with Ansible is to uninstall and re-install RabbitMQ with the variable set.
Also, if you expect manual queue creation with longer TTLs than the defaults, follow the steps in Configure RabbitMQ data directory location to specify additional disk allocation.