NFV repo is supposed to be installed using system packages, as it should
also contain nfvsigdist variable for yum.
So avoid issue with yum update at this step we drop the repo that was
copied from host.
As alternative approach, we can drop copying yum.repos.d at all, but this
can lead to an unexpected results.
Change-Id: Ia5041c7d855a9e988afc4c2a0d16fdeb6a9c357f
3928a0b914