Drop kube-aggregator container image from release

First version of this was only standalone, now the code is being
vendored by anyone who wants to use it. So the standalone binary and
container are no longer useful.

Change-Id: Ib9369de66b4ecb3451f73ba2a252526d6615b96f

hack/lib/golang.sh

@@ -30,7 +30,6 @@ kube::golang::server_targets() {
     cmd/kubeadm
     cmd/hyperkube
     cmd/kube-scheduler
-    vendor/k8s.io/kube-aggregator
     vendor/k8s.io/apiextensions-apiserver
     cluster/gce/gci/mounter
   )
@@ -208,7 +207,6 @@ readonly KUBE_STATIC_LIBRARIES=(
   kube-controller-manager
   kube-scheduler
   kube-proxy
-  kube-aggregator
   kubeadm
   kubectl
 )