chore: test for describe.only without only failure (#34590)

Adds a regression spec for `node:test` `describe.only()` to ensure it
runs successfully without Deno reporting `Test failed because the "only"
option was used`.

The current node:test implementation already registers top-level
node:test entries with `sanitizeOnly: false`; this locks the issue repro
into the spec suite.

Closes denoland/orchid#342
Closes #31862

Verification:
- `/home/orchid/orch-work/issue-342/target/debug/deno test
describe_only.test.js`
- `cargo test -p specs_tests --test specs node_test_describe_only`

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

Author: divybot

tests/specs/node/node_test_describe_only/__test__.jsonc

@@ -0,0 +1,4 @@
+{
+  "args": "test describe_only.test.js",
+  "output": "describe_only.out"
+}

tests/specs/node/node_test_describe_only/describe_only.out

@@ -0,0 +1,9 @@
+running 1 test from ./describe_only.test.js
+a suite ...
+------- output -------
+Test suite is running
+----- output end -----
+a suite ... ok ([WILDCARD])
+
+ok | 1 passed | 0 failed ([WILDCARD])
+

tests/specs/node/node_test_describe_only/describe_only.test.js

@@ -0,0 +1,5 @@
+import { describe } from "node:test";
+
+describe.only("a suite", () => {
+  console.log("Test suite is running");
+});