test: extend async addon test

Test more current behaviour, based on discussions in https://github.com/nodejs/node/pull/14697.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes (presumably … do you know how long make test takes by now?)
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

test/addons

@trevnorris

Quick CI: https://ci.nodejs.org/job/node-test-commit-linuxone/8090/nodes=rhel72-s390x/