test: fix parallel/test-setproctitle.js on alpine

Since Busybox ps does not support -p switch, using ps -o and grep
instead to get the process title and then check it.

PR-URL: https://github.com/nodejs/node/pull/12413
Fixes: https://github.com/nodejs/node/issues/12399


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>