child_process: reduce internal usage of public require of util

PR-URL: #26769
Reviewed-By: Masashi Hirano <shisama07@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/child_process.js

@@ -21,12 +21,14 @@
 
 'use strict';
 
-const util = require('util');
 const {
-  deprecate, convertToValidSignal, getSystemErrorName
+  deprecate,
+  promisify,
+  convertToValidSignal,
+  getSystemErrorName
 } = require('internal/util');
 const { isArrayBufferView } = require('internal/util/types');
-const debug = util.debuglog('child_process');
+const debug = require('internal/util/debuglog').debuglog('child_process');
 const { Buffer } = require('buffer');
 const { Pipe, constants: PipeConstants } = internalBinding('pipe_wrap');
 const {
@@ -170,7 +172,7 @@ const customPromiseExecFunction = (orig) => {
   };
 };
 
-Object.defineProperty(exports.exec, util.promisify.custom, {
+Object.defineProperty(exports.exec, promisify.custom, {
   enumerable: false,
   value: customPromiseExecFunction(exports.exec)
 });
@@ -391,7 +393,7 @@ exports.execFile = function execFile(file /* , args, options, callback */) {
   return child;
 };
 
-Object.defineProperty(exports.execFile, util.promisify.custom, {
+Object.defineProperty(exports.execFile, promisify.custom, {
   enumerable: false,
   value: customPromiseExecFunction(exports.execFile)
 });