Update omnibus to account for multiple mount points
!4657 (merged) introduces a new application setting to select the default repository storage path for the new multiple git mount point feature (see !4578 (merged)). Omnibus must be updated to account for this new setting.
See https://gitlab.com/gitlab-org/gitlab-ee/issues/583 for more details about the feature.
/cc @maratkalibek @marin