use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/k8s.io/api/certificates/v1beta1/doc.go

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 // +k8s:deepcopy-gen=package
+// +k8s:protobuf-gen=package
 // +k8s:openapi-gen=true
 
 // +groupName=certificates.k8s.io

vendor/k8s.io/api/certificates/v1beta1/zz_generated.deepcopy.go

@@ -73,7 +73,7 @@ func (in *CertificateSigningRequestCondition) DeepCopy() *CertificateSigningRequ
 func (in *CertificateSigningRequestList) DeepCopyInto(out *CertificateSigningRequestList) {
 	*out = *in
 	out.TypeMeta = in.TypeMeta
-	out.ListMeta = in.ListMeta
+	in.ListMeta.DeepCopyInto(&out.ListMeta)
 	if in.Items != nil {
 		in, out := &in.Items, &out.Items
 		*out = make([]CertificateSigningRequest, len(*in))