test: backoff client connection rates

We were being very aggressive in our connection creations, resulting
in the pipeline flood detection to drop us. Relax how fast we're
creating these connections so the gc can run all its tests.
src: node.cc use isolate->ThrowException

Environment doesn't have ThrowException, we meant isolate here.

Introduced in commit
75adde07f9a2de7f38a67bec72bd377d450bdb52.
net: fix listening on FDs on Windows

With 3da36fe00e5d85414031ae812e473f16629d8645, I had intended to make
createServerHandle always listen to the handle on Windows.
Unfortunately, I had missed the code path we take when a file
descriptor is passed in.

This fixes test-net-listen-fd0.js on Windows.