Fix Modal Fantom test by flushing message queue

Summary:
The Modal Fantom test was failing in CI with "MessageQueue is not empty" error. This was caused by Modal's componentDidMount subscribing to ModalEventEmitter, which schedules work in the message queue. When Fantom's afterEach hook runs validateEmptyMessageQueue(), it detects pending work and fails the test.

Added Fantom.runWorkLoop() call at the end of the test to flush any pending messages in the queue before the test completes. This follows the established pattern used throughout the Fantom test suite for handling async operations.


Changelog: [Internal] Fix Fantom test

Differential Revision: D88538595

Author: alanleedev

packages/react-native/Libraries/Modal/__tests__/Modal-itest.js

@@ -57,6 +57,9 @@ describe('<Modal>', () => {
             <rn-view />
           </rn-modalHostView>,
         );
+
+        // Flush message queue to handle Modal's componentDidMount event listener setup
+        Fantom.runWorkLoop();
       });
 
       (['slide', 'fade'] as const).forEach(animationType => {