test: check for tls renegotiation errors

Check that the return value and callback error for tls.renegotiate()
does not indicate a failure. Also, remove unnecessary line wrapping and
indentation.

PR-URL: https://github.com/nodejs/node/pull/25437


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>