proxies / mirrormanager / download redirect: fix https/http mixing
    
    Fixes https://pagure.io/fedora-infrastructure/issue/9564
    
    download.fedoraproject.org queries mirrormanager for a redirect to a
    mirror for the path/request. Before we were just taking any mirror that
    mirrormanager had, if it was http or https. This caused requests that
    were sent in as https to get a http mirror and error out. So, now we
    just redirect http ones to http mirrors and https requests to https
    mirrors.
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>