[sdlc] Deploy and configure a self-managed GitLab instance (Omnibus) on the VM

Problem to solve

We need a sandbox instance of the GitLab which will be used to work with siphon and postgres for the whole indexing stack. It should

Proposed solution

Deploy a nightly release of Gitlab Omnibus on the VM. Ensure correct DNS records for the gitlab.gkg.dev Configure it to allow new users from the gitlab.com domain and possibly SSO for debugging convinience.