test: send a bad record only after connection done

Connection is known to be completely setup only after data has
exchanged, so wait unil data echo before sending a bad record.
Otherwise, the bad record could interrupt completion of the server's
handshake, and whether the error is emitted on the connection or server
is a matter of timing.

Also, assert that server errors do not occur. 'error' would crash node
with and unhandled event, but 'tlsClientError' is ignored by default.

PR-URL: https://github.com/nodejs/node/pull/25508


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>