pummel/test-net-throttle assumes that a couple of big write requests result in
some of them getting queued because the kernel's send buffer fills up.
Said assumption breaks on systems with large send buffers. Raise the size of
the write request to ameliorate the issue.
This is a back-port of commit 6770555 from the master branch.
test/simple/test-url.js:31:(0110) Line too long (82 characters).
test/simple/test-url.js:39:(0110) Line too long (85 characters).
test/simple/test-url.js:40:(0110) Line too long (92 characters).