fix: correctly ignore optional dependencies when bundling vite deps

Fixes vitejs#3977
Fixes vitejs#3850

😅 I've accidentally committed the actual fix in vitejs@25d86eb#diff-d17472499351c5bf75d44c67aaa203337dcce321fb578ff05302c61b2b2a3a8aR172

So this PR just removes the erroneous `ingoreDepPlugin`, and moves
the comments to the `ignore` option of the commonjs plugin.

The cause of the issues is this line: https://github.com/websockets/ws/blob/4c1849a61e773fe0ce016f6eb59bc3877f09aeee/lib/buffer-util.js#L105

When we ignore the optional deps when bundling, we expect
`require('bufferutil')` to throw an error.

However, with the previous `ignoreDepPlugin` implementation, the
`require` expression is turned into:
```js
var bufferutil = {
	__proto__: null
};

var require$$1 = /*@__PURE__*/getAugmentedNamespace(bufferutil);

// ...
const bufferUtil = require$$1;
```
No error is throwed, so the code executes into the wrong branch.

After the fix, the `require` expression is left as-is. As `bufferutil`
is not installed in the user project, the error is thrown as expected.

packages/vite/rollup.config.js

@@ -161,14 +161,10 @@ const createNodeConfig = (isProduction) => {
             replacement: `: eval('require'),`
           }
         }),
-      // Optional peer deps of ws. Native deps that are mostly for performance.
-      // Since ws is not that perf critical for us, just ignore these deps.
-      ignoreDepPlugin({
-        bufferutil: 1,
-        'utf-8-validate': 1
-      }),
       commonjs({
         extensions: ['.js'],
+        // Optional peer deps of ws. Native deps that are mostly for performance.
+        // Since ws is not that perf critical for us, just ignore these deps.
         ignore: ['bufferutil', 'utf-8-validate']
       }),
       json(),
@@ -261,26 +257,6 @@ function shimDepsPlugin(deps) {
   }
 }
 
-/**
- * @type { (deps: Record<string, any>) => import('rollup').Plugin }
- */
-function ignoreDepPlugin(ignoredDeps) {
-  return {
-    name: 'ignore-deps',
-    resolveId(id) {
-      if (id in ignoredDeps) {
-        return id
-      }
-    },
-    load(id) {
-      if (id in ignoredDeps) {
-        console.log(`ignored: ${id}`)
-        return ''
-      }
-    }
-  }
-}
-
 function licensePlugin() {
   return license({
     thirdParty(dependencies) {