Allow the gitlab_repmgr password hash to be specified
Related to #2981 (closed); this is failing for the user as they are using some of the advanced configuration (specifing a password hash to the gitlab_repmgr user as mentioned in https://docs.gitlab.com/ee/administration/high_availability/database.html#md5-authentication) out of chef's view, causing the reconfigure to spot a difference.
This should be configurable via gitlab.rb