build: replace `-not` with `!` in `find`

Replace `find -not` usage with `find !` as `-not` is not universally
supported.

Fixes: https://github.com/nodejs/node/issues/24634
PR-URL: https://github.com/nodejs/node/pull/24635


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>