test: revise test-tls-econnreset for OpenSSL 1.1.0

This test is testing what happens to the server if the client shuts off
the connection (so the server sees ECONNRESET), but the way it does it
is convoluted. It uses a static RSA key exchange with a tiny (384-bit)
RSA key. The server doesn't notice (since it is static RSA, the client
acts on the key first), so the client tries to encrypt a premaster and
fails:

  rsa routines:RSA_padding_add_PKCS1_type_2:data too large for key size
  SSL routines:ssl3_send_client_key_exchange:bad rsa encrypt

OpenSSL happens not to send an alert in this case, so we get ECONNRESET
with no alert. This is quite fragile and, notably, breaks in OpenSSL
1.1.0 now that small RSA keys are rejected by libssl. Instead, test by
just connecting a TCP socket and immediately closing it.

PR-URL: https://github.com/nodejs/node/pull/16130


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rod Vagg <rod@vagg.org>