Drop fedora-icon-theme from cinnamon and lxqt desktop groups
    
    See https://bugzilla.redhat.com/show_bug.cgi?id=1853462 . The
    package is no longer installable due to a dependency being
    retired. I determined that these desktops don't default to the
    'Fedora' theme anyway, so they can safely stop including it with
    no ill effects.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>