add lfs support to ubuntu docker runner

As the branch name already says we add large file support to the ubuntu gitlab-runner docker image. The alpine docker already has the same and I was wondering why our tests failed with the dockerized ubuntu runner, but not with the direct runner.

I had to jump through various hoops to just build the docker image and the ubuntu package and then I still had some errors (like dpkg complaining about bzip2 compression). This is the way I build this:

make docker
make build BUILD_PLATFORMS="-os=linux -arch=amd64"
make package-deb-fpm ARCH=amd64 PACKAGE_ARCH=amd64

export DOCKER_MACHINE_VERSION=\"0.14.0\"
export DOCKER_MACHINE_CHECKSUM=\"a4c69bffb78d3cfe103b89dae61c3ea11cc2d1a91c4ff86e630c9ae88244db02\"
export DUMB_INIT_VERSION=\"1.0.2\"
export DUMB_INIT_CHECKSUM=\"a8defac40aaca2ca0896c7c5adbc241af60c7c3df470c1a4c469a860bd805429\"
make release_docker_images

And I still have some local modifications. Is there an easier way?

I hope I adhere to all the contribution rules.