metadata: Change dell svctag metakey to be serialNumber
metadata: Change dell svctag metakey to be serialNumber

This way it matches the windows machines that get the same info from WMI

vimeo/bosun,vimeo/bosun,Dieterbe/bosun,Dieterbe/bosun,Dieterbe/bosun,vimeo/bosun,vimeo/bosun,Dieterbe/bosun