Revert "Add a filtered flathub remote"
    
    This reverts commit a92e8587d0ee49059722fd81ca52cb2797859714.
    
    We probably still want to do this eventually, but the Workstation WG
    believes there are a few issues that require further consideration
    first, including the specifics of the user experience in GNOME Software
    and also whether we want Steam specifically to be included.
    
    Also, we already have Steam as an RPM and don't yet have consensus to
    remove it there.
    
    This will most likely be a temporary revert because flathub is cool.
    
    https://pagure.io/fedora-workstation/issue/108