Change rabbitmq path in startup script

[abbiemery]

The current image uses the shorthand name, but it is better convention to use the full one.The current one is dependent on how you set up your podman, ie, only have the docker registry.

https://github.com/DiamondLightSource/blueapi/blob/main/src/script/start_rabbitmq.sh

Acceptance Criteria

• Change the path in https://github.com/DiamondLightSource/blueapi/blob/main/src/script/start_rabbitmq.sh