Drop Obsoletes cadvisor
    
    Per email from Jan Chaloupka, the Obsoletes cadvisor is no longer needed
    or relevant. From Jan: "This was introduced a long time ago and can be
    safely removed. In the past the kubernetes rpms needed an external
    cadvisor running on a host. After some time the cadvisor code
    was incorporated into the Kubelet. Though, we had to make sure
    the cadvisor rpm got removed during upgrades to new versions of
    kubernetes rpms."