test(node-integration-tests): Surface early scenario exit instead of hanging (#22136)

When a scenario process exits before delivering the envelopes a test
expects — e.g. it throws before sending its transaction, and the
unhandled rejection exits the process with no envelope — the runner kept
waiting until the vitest per-test timeout fired, reporting an opaque
`Test timed out in Nms` with **no child output**. The runner's own 120s
diagnostic dump never ran because the vitest timeout always beat it.
This is why so many Docker/DB integration flakes surface as an
uninformative timeout that only passes on retry.

Now the runner completes the moment the child closes early, with an
error carrying the exit code/signal and how many envelopes arrived vs.
were expected (plus a tail of the child's output in node-core, which has
no separate log dump). Opaque multi-second timeouts become fast,
diagnosable failures across every child-process integration suite.

It only fires for envelope-expecting tests that haven't completed: the
success path has already called `complete()` (so this is a no-op),
server-style (`makeRequest`) tests are killed by `complete()` first, and
`ensureNoErrorOutput` / no-envelope tests are unaffected.

_Verified locally_: a scenario that throws before sending an envelope
now fails in ~0.5s with `Scenario exited (code 1) after 0/1 expected
envelope(s), before the test completed.` instead of hanging; normal
envelope-then-exit suites (cron), server-style suites
(httpIntegration-streamed), and the ANR suite (incl. `should exit`,
which expects no envelopes) all still pass.

This does not by itself fix a specific flaky test — it makes the next
occurrence diagnosable. In particular it unblocks root-causing the cron
timeouts (#22112, #21891), whose real cause is currently hidden behind
the opaque timeout.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mydea

dev-packages/node-integration-tests/utils/runner/createRunner.ts

@@ -480,11 +480,30 @@ export function createRunner(...paths: string[]) {
             }
           });
 
-          child.on('close', () => {
+          child.on('close', (code, signal) => {
             hasExited = true;
 
             if (ensureNoErrorOutput) {
               complete();
+              return;
+            }
+
+            // A scenario that still owes envelopes but has already exited will never deliver them.
+            // Without this, `completed()` blocks until the vitest test timeout and reports an opaque
+            // "Test timed out", hiding the real failure (e.g. the scenario threw before sending its
+            // transaction — an unhandled rejection exits the process with no envelope). Complete with
+            // the exit status and how far we got so the failure is fast and diagnosable; the captured
+            // child output is dumped by `completed()`. In the success path `complete()` has already
+            // run (so `isComplete` short-circuits this), server-style tests are killed by `complete()`
+            // first, and tests that expect no envelopes drive completion some other way.
+            if (!isComplete && expectedEnvelopeCount > 0) {
+              const how = signal ? `signal ${signal}` : `code ${code ?? 'unknown'}`;
+              complete(
+                new Error(
+                  `Scenario exited (${how}) after ${envelopeCount}/${expectedEnvelopeCount} expected ` +
+                    'envelope(s), before the test completed.',
+                ),
+              );
             }
           });