Skip clone repository while GIT_DEPTH set to zero.

Closed username-removed-495698 requested to merge rekby/gitlab-ci-multi-runner:git-depth-0 into master

The merge request skip clone of git repository when GIT_DEPTH set to 0.

I have a large repository and WAN connection to the repostitory from test servers. It take a lot of time to clone repository, when I doesn't need it to test. I need only compiled binaries.