gitlab.rb.template incorrectly includes values from default.rb
Check these lines https://gitlab.com/gitlab-org/omnibus-gitlab/blob/23cd894b945b138099c0fe9417fd6e349c152ba3/files/gitlab-config-template/gitlab.rb.template#L1254-1283.
The default['gitlab']['
prefix should be removed, and also underscores should be used instead of dashes. See discussion in https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1132/diffs#note_22997360.
We should be careful where dashes/underscores are used.