Don't run 20-grub.install for UKIs
    
    When kernel-install is called for a UKI, 20-grub.install copies it to /boot
    which is totally unneeded, UKIs are now handled by the standard systemd's
    90-uki-copy.install (systemd-253+) correctly which places them to the ESP.
    
    Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>