/usr/lib/rabbitmq/bin/rabbitmq-plugins is in rabbitmq-server 3.2.4-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/rabbitmq/bin/../lib/rabbitmq_server-3.2.4/sbin/rabbitmq-plugins
/usr/lib/rabbitmq/bin/../lib/rabbitmq_server-3.2.4/sbin/rabbitmq-plugins