test: replace http-destroyed-socket-write

As a comment in the test states: "This test should not be ported to
v0.10 and higher, because the problem is fixed by not ignoring
ECONNRESET in the first place."

The test is checking whether write returns false instead of whether an
ECONNRESET has been raised.

Replace with test-http-destroyed-socket-write2, this test verifies that
ECONNRESET is raised when writing to an http request where the server
has destroyed the socket.

Signed-off-by: Timothy J Fontaine <tjfontaine@gmail.com>
stream: don't try to finish if buffer is not empty

fixes #5715