test: permit test-graph.signal to work without test runner

test/async-hooks/test-graph.signal.js passes with the test.py test
runner but fails if run directly with the `node` executable. Modify
the test so it passes in both cases.

PR-URL: #28305
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/async-hooks/test-graph.signal.js

@@ -53,7 +53,11 @@ function onexit() {
       { type: 'PIPEWRAP', id: 'pipe:4', triggerAsyncId: 'signal:1' },
       { type: 'PIPEWRAP', id: 'pipe:5', triggerAsyncId: 'signal:1' },
       { type: 'PIPEWRAP', id: 'pipe:6', triggerAsyncId: 'signal:1' },
-      { type: 'SIGNALWRAP', id: 'signal:2', triggerAsyncId: 'signal:1' },
+      { type: 'SIGNALWRAP', id: 'signal:2',
+        // TEST_THREAD_ID is set by tools/test.py. Adjust test results depending
+        // on whether the test was invoked via test.py or from the shell
+        // directly.
+        triggerAsyncId: process.env.TEST_THREAD_ID ? 'signal:1' : 'pipe:2' },
       { type: 'PROCESSWRAP', id: 'process:3', triggerAsyncId: 'signal:1' },
       { type: 'PIPEWRAP', id: 'pipe:7', triggerAsyncId: 'signal:1' },
       { type: 'PIPEWRAP', id: 'pipe:8', triggerAsyncId: 'signal:1' },