Use DOCKER_SOCKET_PATH for pulling sibling container images

Steps to Reproduce

1. Enable sibling containers and set DOCKER_SOCKET_PATH to custom docker.sock
2. Enable automatic sibling container pulling: SIBLING_CONTAINERS_PULL=true
3. Start overleaf: bin/up

Expected Behaviour

Docker images should get pulled through the same docker.sock that will receive run commands for sibling containers.

Observed Behaviour

Images for sibling containers get pulled through the default docker.sock of the host system.

Context

Personally I don't like giving a container access to the hosts docker.sock, basically giving it access to other containers as well.
That's why I wanted to set up a docker in docker (DinD) setup, where I provide a separate docker.sock from the docker - docker container. This already works well, but I have to pull needed sibling container images manually inside the DinD container before I can use them in Overleaf.

Optionally (for my DinD case)

It would be great if the sibling image pulling could get timed somehow to make sure the docker.sock is available.
I don't know how doable this is, but maybe just polling the socket until it becomes available could be a good start.

Start with bin/up and trace the sibling-container image-pulling path used when SIBLING_CONTAINERS_PULL=true. Check how DOCKER_SOCKET_PATH is passed to pulls versus sibling-container run commands, then verify that images are pulled through the configured socket, including the DinD case if feasible.