test: remove `common.PORT` from test-tlswrap

`test/async-hooks/test/test-tlswrap.js` uses `common.PORT` but
async-hooks tests are run in parallel. Another test using port 0 could
result in a port collision. Remove `common.PORT` from the test.

PR-URL: https://github.com/nodejs/node/pull/15742
Ref: https://github.com/nodejs/node/issues/14404#issuecomment-333672346


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>