files: mark /run/motd as an ephemeral ghost entry
    
    This stops installing an empty /run/motd file, marking it as a
    ghost entry instead.
    Nowadays, /run is an ephemeral location which can get regularly
    cleaned (e.g. on reboot), discarding such installed file too.
    This package already ships a tmpfiles.d entry to properly create
    /run/motd both on install and on subsequent boots. As such, it is
    enough to claim the ownership of that filepath in the rpmdb.