Migrate support access to use new console/dbconsole mechanism

Currently, members of support group have access to web-01: https://gitlab.com/gitlab-cookbooks/gitlab_users/#support, added as result of the https://gitlab.com/gitlab-com/infrastructure/issues/2498#note_39300808.

Since there's a better way of accessing rails and db consoles -- https://gitlab.com/gitlab-com/runbooks/blob/master/howto/granting-rails-or-db-access.md -- we should migrate support group to it and clean up gitlab_users.

Plan:

• Add every member of support group to the rails_users role, both on staging and production. Users: @arihantar, @cpallares, @dblessing and @markglenfletcher. (MR: https://dev.gitlab.org/cookbooks/chef-repo/merge_requests/1328)
• Move users from support group to vpn group (Group update MR: https://dev.gitlab.org/cookbooks/chef-repo/merge_requests/1328)
• @arihantar (the only one who have vpn group membership)
• @cpallares
• @dblessing
• @markglenfletcher
• Make sure everyone knows how to access the rails console new way. Make sure that we don't need separate postgres console access.
• Delete support group from user and roles databags (same MR: https://dev.gitlab.org/cookbooks/chef-repo/merge_requests/1328 ).
• Delete support group from gitlab_users ( MR: https://gitlab.com/gitlab-cookbooks/gitlab_users/merge_requests/32 ).
• Update cookbook across all environments.

/cc @jarv @pcarranza