*: Revert nodeversion.mk changes.

The intention was to avoid nodejs-18.x which no longer supports older
platforms, but that didn't work as pbulk still chooses the latest anyway, so
we'll need to fix that a different way.

It also has the downside of tying them to a specific version, which meant you
could no longer use the npm or yarn package managers with anything other than
the default nodejs version.

(jperkin)