test: run the addon tests last

Running the addon tests before the parallel, sequential, etc. tests
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.

Running the addon tests last fixes this.

Refs: https://github.com/nodejs/node/issues/12031
PR-URL: https://github.com/nodejs/node/pull/12062


Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>