Change etcd image tag (#330)

Change etcd image to what it used to be due to lack of sh in the base
image.
Use absolute path for bootstrap script.

Author: mengqiy

operator/pkg/controllers/etcd/pod.go

@@ -80,7 +80,7 @@ func podSpecFor(controlPlane *v1alpha1.ControlPlane) *v1.PodSpec {
 				MountPath: "/etc/kubernetes/",
 			}},
 			Command: []string{
-				"./etc/kubernetes/bootstrap.sh",
+				"/etc/kubernetes/bootstrap.sh",
 			},
 			Args: []string{
 				"--cert-file=/etc/kubernetes/pki/etcd/server/server.crt",

operator/pkg/utils/imageprovider/imageprovider.go

@@ -57,7 +57,7 @@ func KubeProxy(version string) string {
 }
 
 func ETCD() string {
-	return repositoryName + "etcd-io/etcd:v3.5.4-eks-1-23-9"
+	return repositoryName + "etcd-io/etcd:v3.4.16-eks-1-21-4"
 }
 
 func CoreDNS() string {