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/istio.io/client-go/pkg/informers/externalversions/internalinterfaces/factory_interfaces.gen.go

@@ -0,0 +1,24 @@
+// Code generated by informer-gen. DO NOT EDIT.
+
+package internalinterfaces
+
+import (
+	time "time"
+
+	versioned "istio.io/client-go/pkg/clientset/versioned"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	runtime "k8s.io/apimachinery/pkg/runtime"
+	cache "k8s.io/client-go/tools/cache"
+)
+
+// NewInformerFunc takes versioned.Interface and time.Duration to return a SharedIndexInformer.
+type NewInformerFunc func(versioned.Interface, time.Duration) cache.SharedIndexInformer
+
+// SharedInformerFactory a small interface to allow for adding an informer without an import cycle
+type SharedInformerFactory interface {
+	Start(stopCh <-chan struct{})
+	InformerFor(obj runtime.Object, newFunc NewInformerFunc) cache.SharedIndexInformer
+}
+
+// TweakListOptionsFunc is a function that transforms a v1.ListOptions.
+type TweakListOptionsFunc func(*v1.ListOptions)