tools: improve update-eslint.sh

* Pin version numbers when using `npx`. This means we can be careful
  about updating what we run. (Thinking about the recent eslint-scope
  thing.)
* Add removeNPMAbsolutePaths to get rid of unused fields in package.json
  files. These unused fields can cause unnecessary churn, as at least
  one contains an absolute path that will be different for each
  developer.

PR-URL: https://github.com/nodejs/node/pull/21819


Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>