plugins: Eliminate unnecessary run_npm.js

I had anticipated more shared logic than we actually need (the
abstraction in `run_npm.js` is YAGNI).

src/node/utils/run_npm.js

@@ -1,39 +0,0 @@
-'use strict';
-
-const log4js = require('log4js');
-const runCmd = require('./run_cmd');
-
-const logger = log4js.getLogger('runNpm');
-
-/**
- * Wrapper around `runCmd()` to make it easier to run npm.
- *
- * @param args Command-line arguments to pass to npm.
- * @param opts See the documentation for `runCmd()`.
- *
- * @returns A Promise with additional `stdout`, `stderr`, and `child` properties. See the
- *     documentation for `runCmd()`.
- */
-module.exports = exports = (args, opts = {}) => {
-  const cmd = ['npm', ...args];
-  // MUST return the original Promise returned from runCmd so that the caller can access stdout.
-  return runCmd(cmd, opts);
-};
-
-// Log the version of npm at startup.
-let loggedVersion = false;
-(async () => {
-  if (loggedVersion) return;
-  loggedVersion = true;
-  const p = runCmd(['npm', '--version'], {stdoutLogger: null});
-  const chunks = [];
-  await Promise.all([
-    (async () => { for await (const chunk of p.stdout) chunks.push(chunk); })(),
-    p, // Await in parallel to avoid unhandled rejection if p rejects during chunk read.
-  ]);
-  const version = Buffer.concat(chunks).toString().replace(/\n+$/g, '');
-  logger.info(`npm --version: ${version}`);
-})().catch((err) => {
-  logger.error(`Failed to get npm version: ${err.stack}`);
-  // This isn't a fatal error so don't re-throw.
-});