Run 'docker pull' in test scenarios to make sure Docker images come from Pyrsia node

[ihcomega56]

pyrsia-integration-tests/bats/tests/pyrsia_node_docker_build_service.bats

Line 80 in 72d4d55

# check if the built image can be pulled from the Pyrsia node

Currently a test for docker pull does not run this command directly, but just check if a Pyrsia node has a specific image using Docker registry API because a way to check where Docker images are pulled from is not found.

We should find the solution for it and execute an actual docker pull command to make sure they are downloaded from a Pyrsia node instead of docker.io.

[betarelease]

I think this is good enough for now.
This might be the solution we have to live with for some time since there is not difference in images on Pyrsia and docker so the only way to verify is that this image is found in Pyrsia and due to the remotes definition in the configuration Pyrsia will serve it.
So I am going to move this to backlog and deprioritize.