stream: fix end-of-stream for HTTP/2

HTTP/2 streams call `.end()` on themselves from their
`.destroy()` method, which might be queued (e.g. due to network
congestion) and not processed before the stream itself is destroyed.

In that case, the `_writableState.ended` property could be set before
the stream emits its `'close'` event, and never actually emits the
`'finished'` event, confusing the end-of-stream implementation so
that it wouldn’t call its callback.

This can be fixed by watching for the end events themselves using the
existing `'finish'` and `'end'` listeners rather than relying on the
`.ended` properties of the `_...State` objects.

These properties still need to be checked to know whether stream
closure was premature – My understanding is that ideally, streams
should not emit `'close'` before `'end'` and/or `'finished'`, so this
might be another bug, but changing this would require modifying tests
and almost certainly be a breaking change.

Fixes: https://github.com/nodejs/node/issues/24456

PR-URL: https://github.com/nodejs/node/pull/24926


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>