Gitlab Shell no longer uses repository path
gitlab_shell['git_data_directories'] is obsolete configuration. It is no longer being passed to gitlab-shell.
The code in libraries/gitlab_shell.rb is no longer needed in the current form. It also no longer belongs to gitlab-shell.
This section be refactored and simplified. We should extract the deprecated configuration. With addition of Gitaly, these configuration options are shared between Rails and Gitaly.