Bootsnap speeds up Rails loading and now ships by default with Rails 5.2
apps. We should promote this to a default gem and test it out in
production. This will also make it possible for the Helm Charts to take
advantage of this.

It appears that Bootsnap with Rails 5.2.3 and all the GitLab CE gems
loads fine on an ARM platform now, so it's possible that
https://gitlab.com/gitlab-org/gitlab-ce/issues/34799 has been resolved.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/45230