[Meta] Trim the package size
This is a holding issue with the topic of trimming unnecessary parts from the package.
There are already a couple of issues touching this topic: https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1537, https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1643, https://gitlab.com/gitlab-org/omnibus-gitlab/issues/988
Since we are putting more things in the package with Prometheus, the time has come to add some resources towards removing unnecessary parts of the package.
Prime candidates to save a few KB's are:
- All software definitions cloned from git can have specs removed (some of them also docs). GitLab Rails still needs the doc directory
- Gems with native extensions need to have a build cleanup after
- Further investigate which software definitions can be removed as they are used as a build dependency and not a runtime dependency
- More...