test: replace common.PORT with `0` in https renegotiation test

Repeated use of common.PORT was resulting in sporadic failures on some
operating systems.

PR-URL: https://github.com/nodejs/node/pull/25599


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>