doc: remove unadvisable cluster example

Applications should usually keep track of workers themselves to prevent
cross-referencing workers from different "groups" that are assigned to
separate tasks.

Additionally, it is unreasonable to assume that the 'data' event emitted
by a socket object will be an integer. While the example works when the
argument is a string (or Buffer), it can result in various issues (e.g.,
when id === '__proto__' since cluster.workers has a non-null prototype).

Refs: 5f08c3c

PR-URL: #41668
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tierney Cyren <hello@bnb.im>

doc/api/cluster.md

@@ -1087,14 +1087,6 @@ for (const worker of Object.values(cluster.workers)) {
 }
 ```
 
-Using the worker's unique id is the easiest way to locate the worker.
-
-```js
-socket.on('data', (id) => {
-  const worker = cluster.workers[id];
-});
-```
-
 [Advanced serialization for `child_process`]: child_process.md#advanced-serialization
 [Child Process module]: child_process.md#child_processforkmodulepath-args-options
 [`.fork()`]: #clusterforkenv