test: tweak addon tests

[mscdex]

• Version: all
• Platform: n/a
• Subsystem: test

Currently we run the addon tests before the parallel, sequential, etc. tests which can be a problem if there is a bug in node that prevents the addon tests from running properly. When the addon tests fail for any reason, then none of the other tests (e.g. parallel, etc.) are executed.

So I propose we either allow test execution to continue when any of the addon tests fail (saving the status code in case the rest of the tests should pass) or we simply move the addon tests to run after the parallel, etc. tests.

/cc @nodejs/collaborators

[bnoordhuis]

Let's go with the easiest solution: run the addon tests last.