io/ioutil has already been deprecated in golang 1.16, so replace all ioutil with io and os

test/e2e_node/util.go

@@ -22,7 +22,7 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"os/exec"
 	"regexp"
@@ -95,7 +95,7 @@ func getNodeSummary() (*stats.Summary, error) {
 	}
 
 	defer resp.Body.Close()
-	contentsBytes, err := ioutil.ReadAll(resp.Body)
+	contentsBytes, err := io.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read /stats/summary: %+v", resp)
 	}