test: fix tls-inception

Make sure all the data is read before checking its validity.
Remove `gotHello` variable and just check that the ssl `end` event
is received.
Remove unused variables.

PR-URL: https://github.com/nodejs/node/pull/4195


Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Fedor Indutny <fedor@indutny.com>