https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/24624 extracted
the X-Forwarded-For address directly, but this didn't consider the case
where multiple proxies are in the chain. To fix this, we use the Rails
implementation to filter trusted proxies, as documented by Grape:
https://github.com/ruby-grape/grape#remote-ip

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/58103