stream: update comment to indicate unused API

destroy w/ callback was previously used by node
core. This is no longer the case and the
comments should reflect this to avoid confusion.

PR-URL: #32808
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/internal/streams/destroy.js

@@ -1,15 +1,13 @@
 'use strict';
 
-// Undocumented cb() API, needed for core, not for public API.
-// The cb() will be invoked synchronously if _destroy is synchronous.
-// If cb is passed no 'error' event will be emitted.
+// Backwards compat. cb() is undocumented and unused in core but
+// unfortunately might be used by modules.
 function destroy(err, cb) {
   const r = this._readableState;
   const w = this._writableState;
 
   if ((w && w.destroyed) || (r && r.destroyed)) {
     if (typeof cb === 'function') {
-      // TODO(ronag): Invoke with `'close'`/`'error'`.
       cb();
     }