http2: emit close event if request aborted

Fix Http2ServerRequest and Http2ServerResponse to emit close event
if the request is aborted before response.end can be called.

Fixes: https://github.com/nodejs/node/issues/15385
PR-URL: https://github.com/nodejs/node/pull/15415


Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>