Fix npm ENOENT error in install-script-runner-dependencies

Despite what atom#23322 is named,
the pull request actually makes install-script-dependencies
use the non-local npm binary.

So this pr fixes install-script-runner-dependencies by making the npmBinPath
consistent with install-script-dependencies

ENOENT detected by #351,
specifically https://dev.azure.com/atomcommunity/atomcommunity/_build/results?buildId=1132&view=logs&j=2985f0af-e798-5fdc-91b8-be9f0a3685c5&t=0a53f124-4db9-5fc3-be81-e293757effc7&l=16

Author: icecream17

apm/package-lock.json

@@ -3,6 +3,7 @@
 
 'use strict';
 
+const fs = require('fs');
 const path = require('path');
 const spawnSync = require('./lib/spawn-sync');
 
@@ -111,14 +112,6 @@ function getApmBinPath() {
   );
 }
 
-function getNpmBinPath(external = false) {
-  const npmBinName = process.platform === 'win32' ? 'npm.cmd' : 'npm';
-  const localNpmBinPath = path.resolve(
-    repositoryRootPath,
-    'script',
-    'node_modules',
-    '.bin',
-    npmBinName
-  );
-  return localNpmBinPath;
+function getNpmBinPath() {
+  return process.platform === 'win32' ? 'npm.cmd' : 'npm';
 }

script/config.js

@@ -9,9 +9,8 @@ process.env.ELECTRON_CUSTOM_VERSION = CONFIG.appMetadata.electronVersion;
 
 module.exports = function(ci) {
   console.log('Installing script dependencies');
-  const npmBinName = process.platform === 'win32' ? 'npm.cmd' : 'npm';
   childProcess.execFileSync(
-    npmBinName,
+    CONFIG.getNpmBinPath(ci),
     ['--loglevel=error', ci ? 'ci' : 'install'],
     { env: process.env, cwd: CONFIG.scriptRootPath }
   );