tools: replace deprecated ESLint configuration

For `globals`, booleans are deprecated in favor strings
`'readable'`/`'writeable'`.

PR-URL: https://github.com/nodejs/node/pull/25877


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>