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/sigs.k8s.io/controller-runtime/pkg/healthz/doc.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package healthz contains helpers from supporting liveness and readiness endpoints.
+// (often referred to as healthz and readyz, respectively).
+//
+// This package draws heavily from the apiserver's healthz package
+// ( https://github.com/kubernetes/apiserver/tree/master/pkg/server/healthz )
+// but has some changes to bring it in line with controller-runtime's style.
+//
+// The main entrypoint is the Handler -- this serves both aggregated health status
+// and individual health check endpoints.
+package healthz
+
+import (
+	logf "sigs.k8s.io/controller-runtime/pkg/internal/log"
+)
+
+var log = logf.RuntimeLog.WithName("healthz")