[docs][Backdrop] Move Backdrop to Utils and clarify it is a low-level utility - #49072

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: mnajdova/github-action-required-labels@ca0df9249827e43aa4b4a0d25d9fe3e9b19b0705. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/