all: replace uses of ioutil with io and os (#24869)

node/rpcstack.go

@@ -21,7 +21,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"sort"
@@ -444,7 +443,7 @@ func (h *virtualHostHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 var gzPool = sync.Pool{
 	New: func() interface{} {
-		w := gzip.NewWriter(ioutil.Discard)
+		w := gzip.NewWriter(io.Discard)
 		return w
 	},
 }