fix(ext/node): wire ConnectionsList hooks so headersTimeout doesn't spuriously fire (#34356)
The JS-based `ConnectionsList` introduced in #33208 (the `node:http`
rewrite) defines `markHeadersCompleted()` and `popActive()` methods to
mirror Node's native C++ binding, but only the initial `pushActive()`
was ever called from `connectionListenerInternal` — the other two were
defined and never invoked. Node's C++ wires these into the HTTP parser
callbacks (`on_message_begin` / `on_headers_complete` /
`on_message_complete`); the JS port forgot to do the same.
As a result every server connection sat in `_active` with
`headersCompleted: false` and a fixed `startTime`, so the 30s
`checkConnections` watchdog fired a spurious `ERR_HTTP_REQUEST_TIMEOUT`
about 60 seconds into any long-running request. Fastify's default
`clientError` handler converts that error into HTTP 400, which is the
user-visible regression. The fix mirrors Node's behavior in JS:
`parser[kOnMessageBegin]` does popActive + pushActive (also covers the
keepalive case so a second request on the same socket gets a fresh
window), `parserOnIncoming` calls `markHeadersCompleted` once headers
are parsed, and `resOnFinish` calls `popActive` when the response is
done.
Fixes #34297