test: apply eslint exceptions narrowly

In test-util-inspect, apply ESLint exception for accessor-pairs rule
narrowly. It had been applied to nearly the whole file, but is only
needed for two lines.

PR-URL: https://github.com/nodejs/node/pull/16393


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>