Hide modified repositories from the output of 'fedora-third-party list'
    
    When a Flatpak repository (such as the Fedora Flathub Selection) repository
    is modified to remove the filter (typically by reinstalling a new
    flatpakrepo file for the same repository), hide it from the
    'fedora-third-party list' output, so that a tool like GNOME Software
    will no longer display it as a third-party repository.