kubectl_test: use more meaningful expecter
kubectl_test: use more meaningful expecter

Expect(result).ToNot(BeEmpty()) would fail more meaningfully

Signed-off-by: Dan Kenigsberg <184831158ae7531bcabc22617ed51e8717c81e93@redhat.com>

kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt