Warning as someone who just did that. MySQL is EE only on Omnibus. I switched from Source (MySQL) to Omnibus only to find that MySQL was EE only.
So I had to go back to Source.
So I had to go back to Source.
Switching away from MySQL might not be an option for you but documentation on how to convert from MySQL to PostgreSQL can be found on https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc...