chore: regression test for process._getActiveHandles() in 'exit' handler (#34191)

## Summary

Adds a regression test that pins the fix from #34101 against the exact
reproduction in [#34187](#34187):
a CJS module that lazy-loads `node:http` via `setImmediate`, then calls
`process._getActiveHandles()` (plus `_getActiveRequests` /
`getActiveResourcesInfo`) from a `process.on('exit', ...)` handler.

Before #34101 this threw `TypeError: process._getActiveHandles is not a
function`. With the active-process-resources polyfills now in place, the
snippet runs and prints `[]` like Node does. The new spec test ensures
we don't regress.

## Test plan

- [x] `cargo test --package specs_tests --test specs
node::process_get_active_handles_on_exit` passes
- [x] Running `target/debug/deno run -A repro.cjs` matches Node's
behavior

Closes denoland/orchid#131

Co-authored-by: divybot <divybot@users.noreply.github.com>
Co-authored-by: Divy Srivastava <me@littledivy.com>

Author: divybot

tests/specs/node/process_get_active_handles_on_exit/__test__.jsonc

@@ -0,0 +1,8 @@
+{
+  "tests": {
+    "get_active_handles_on_exit": {
+      "args": "run -A repro.cjs",
+      "output": "handles=0\nrequests=0\nok\n"
+    }
+  }
+}

tests/specs/node/process_get_active_handles_on_exit/repro.cjs

@@ -0,0 +1,29 @@
+// Regression test for https://github.com/denoland/deno/issues/34187
+// `process._getActiveHandles()` must be callable from the `'exit'` event
+// handler in a CJS module that lazy-loads `node:http`.
+
+setImmediate(function () {
+  require("http");
+});
+
+var i = setInterval(function () {
+  setImmediate(process.exit);
+}, 10);
+i.unref();
+
+process.on("exit", logstuff);
+
+function logstuff() {
+  if (typeof process._getActiveHandles !== "function") {
+    throw new TypeError("process._getActiveHandles is not a function");
+  }
+  if (typeof process._getActiveRequests !== "function") {
+    throw new TypeError("process._getActiveRequests is not a function");
+  }
+  if (typeof process.getActiveResourcesInfo !== "function") {
+    throw new TypeError("process.getActiveResourcesInfo is not a function");
+  }
+  console.log("handles=" + process._getActiveHandles().length);
+  console.log("requests=" + process._getActiveRequests().length);
+  console.log("ok");
+}