[AI Improvement] [Task] Prevent unclosed Admin SDK connections and eliminate 5s sleep in extensions-emulator tests

[joehan]

Resolves Buganizer b/563476480

Proposed Improvement

1. Added clean Admin SDK teardown in after() hook (await Promise.all(admin.apps.map((app) => app?.delete()))) in scripts/extensions-emulator-tests/tests.ts to close gRPC channels, active sockets, and event loop handles.
2. Replaced the 5-second blind sleep with an active polling helper (pollForExtensionOutput) that checks Storage and Firestore emulator outputs every 100ms with a 15-second timeout, allowing the test to pass as soon as the extension finishes writing.

Verification

• Ran npm run build - passed.
• Ran npm run lint - passed.
• Ran npm test -- src/test/emulators/ - all 128 tests passing.
• Ran static type checks with tsc - clean.

[gemini-code-assist]

Code Review

This pull request replaces a static write delay in the extensions emulator tests with a polling mechanism ('pollForExtensionOutput') that waits for the resized file and Firestore document, and adds cleanup of Firebase admin apps in the 'after' hook. Feedback suggests flattening the nested 'if' statements inside the polling function's 'try' block to reduce nesting, adhering to the repository's style guide.

[joehan]

LGTM

[ajperel]

🟡 Nit: Ensure cleanUpExtensionsCache() and test.stopEmulators() run even if app.delete() rejects

Rationale: If any app.delete() call rejects during teardown (or if before() fails before test is assigned), cleanUpExtensionsCache() and test.stopEmulators() would be skipped, leaving emulator child processes running.

Suggested Fix:

    await Promise.allSettled(admin.apps.map((app) => app?.delete()));
    cleanUpExtensionsCache();
    await test?.stopEmulators();

[joehan]

Good catch! Updated to Promise.allSettled(admin.apps.map((app) => app?.delete())) and guarded await test?.stopEmulators() so emulator cleanup always runs even if Admin SDK deletion rejects.