process: use owner_symbol for `_getActive*`

This makes it easier to provide public APIs in the return types
of `process._getActiveHandles()` and `process._getActiveRequests()`.

PR-URL: https://github.com/nodejs/node/pull/22002


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>