add helper_image option to docker executor config
What does this MR do?
helper_image config option to docker executor
Why was this MR needed?
We actively use git-lfs in our projects. Currently git-lfs version change impossible without upgrade of gitlab-runner.
But we need to regulary upgrade git and git-lfs for performance improvements and bug fixes. This MR allows us to have internal docker image based on
gitlab/gitlab-runner-helper with latest versions for git and git-lfs.
Are there points in the code the reviewer needs to double check?
Does this MR meet the acceptance criteria?
- Documentation created/updated
- Added for this feature/bug
- All builds are passing
Branch has no merge conflicts with
master(if you do - rebase it please)