timers: use custom inspection for linked lists

Inspecting linked lists is something that is not really useful.
Instead, just use a custom inspection function and hide everything
besides the first level.

PR-URL: https://github.com/nodejs/node/pull/23108


Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>