Modify Puma's default workers count on Geo Secondary roles
For unicorn, we update the default workers count on Geo Secondary roles - https://gitlab.com/gitlab-org/omnibus-gitlab/blob/72263fdffa252f22ce766947e2fdbbd2636f714c/files/gitlab-cookbooks/package/libraries/config/roles/geo_secondary.rb#L43-45
We should check if we want to do something similar for Puma also. Followup from !4000 (merged).
/cc @bjk-gitlab