.gitlab-ci.yml: Use `dockerd-entrypoint.sh` script for the test job
dockerd-entrypoint.sh
is part of the docker:dind
image and ensures that the right version of iptables
is used, depending on the kernel configuration. This is required to fix e2e CI with the latest Docker images.
See also https://github.com/docker-library/docker/pull/465.
This branch also disables the GitLab CI dind service for the test job as that's redundant when we directly start dockerd
.