I know this is an old question but I was facing the same issue recently and unfortunately I still haven't found an official portable version.

Following @Furkan's answer, I created an automated workflow to create portable releases for RabbitMQ. You can find it here: https://github.com/sb-ghvcs/rabbitmq-portable

It does the same steps as @Furkan's answer temperorily within a contained shell without affecting rest of the system.