Since they are sent after the handshake in TLS 1.3, the client was not
actually consuming them, as it doesn't make any Read calls. They were
then sitting in the kernel receive buffer when the client would call
Close. The kernel would see that and send a RST, which would race the
closeNotify, causing errors.

Also, we get to trim 600 lines of useless test data.

Fixes #28852

Change-Id: I7517feab77dabab7504bfc111098ba09ea07ae5e
Reviewed-on: https://go-review.googlesource.com/c/151659Reviewed-by: Ian Lance Taylor <iant@golang.org>