Regression fix: allow multiple docker projects of the same govcms project at the same time

[silverham]

Due to the container_name in the docker-compose.yml for the service cli not being dynamic (or absent which infers it being dynamic automatically), if i run two two of the same govcms projects with the same name, I get a naming conflict.

Preferred solution: use additional_contexts to container depending locally on each other.
@see https://docs.docker.com/compose/how-tos/dependent-images/#use-another-services-image-as-the-base-image

Quick fix solution (this PR):
-> Remove container_name (so its dynamic)
-> Set image name to be dynamic so other dependancies so the new image name built. (not preferred because docker compose build --pull breaks.

[steveworley]

Thanks @silverham — I'll get this tested and then merged and added to the next release.