Remove env var DOCKER_HOST for Docker.mountDockerSocket
Remove env var DOCKER_HOST for Docker.mountDockerSocket.
Checking /var/run/docker.sock is the default anyway.
The env var causes an issue with spring boot maven plugin when running maven inside a container:
https://github.com/spring-projects/spring-boot/issues/22300
Unfortunately, unsetting the var with "withEnv(['DOCKER_HOST='])" does not work, but setting an env var would work.
So we remove the env var here, if anyone should need it (even though it's the default behavior!) it can just be set using
"withEnv(['DOCKER_HOST=unix:///var/run/docker.sock'])".