doc: revise "Breaking Changes to Internal Elements"

Revise the "Breaking Changes to Internal Elements" section of
COLLABORATOR_GUIDE.md. Simplify wording, shorten sentences, and remove
redundant material.

PR-URL: https://github.com/nodejs/node/pull/25190


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>