/usr/lib/rabbitmq/bin/rabbitmq-env is in rabbitmq-server 3.5.7-1ubuntu0.16.04.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/rabbitmq/bin/../lib/rabbitmq_server-3.5.7/sbin/rabbitmq-env
/usr/lib/rabbitmq/bin/../lib/rabbitmq_server-3.5.7/sbin/rabbitmq-env