test: fix flaky test-inspector

Using `socket.destroy()` instead of `socket.end()` fixes
more-than-intermittent ECONNRESET issues on Windows.

PR-URL: https://github.com/nodejs/node/pull/9727
Fixes: https://github.com/nodejs/node/issues/8804


Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>