scheduler/cups.service.in: Use nss-user-lookup.target in "After="
scheduler/cups.service.in: Use nss-user-lookup.target in "After="

Start cupsd after nss-user-lookup.target has been reached, instead of
listing every service that could provide username resolution (sssd,
ypbind, nslcd, etc.) to the "After=" line in the systemd unit file.

OpenPrinting/cups,OpenPrinting/cups,OpenPrinting/cups,OpenPrinting/cups