Draft: Clone gitlabsos recursively, for sanitizer

The gitlabsos script can use the gitlab.rb sanitizer automatically, if it's present on the host in sanitizer/sanitizer.rb within the working copy. This is added as a git submodule of the gitlabsos repository already.

This MR sets the Ansible group_vars/all.yml gitlab_recursive to true so that — by default — the sanitizer will be cloned as well, and SOS bundles will contain each server's sanitized GitLab settings in etc/gitlab/gitlab.rb