test(ai): update vertex ai live model name

Replaces the deprecated `gemini-2.0-flash-exp` with
`gemini-2.0-flash-live-preview-04-09`.

Author: dlarocque

packages/ai/integration/constants.ts

@@ -57,7 +57,7 @@ const modelNames: readonly string[] = ['gemini-2.0-flash', 'gemini-2.5-flash'];
 // The Live API requires a different set of models, and they're different for each backend.
 const liveModelNames: Map<BackendType, string[]> = new Map([
   [BackendType.GOOGLE_AI, ['gemini-live-2.5-flash-preview']],
-  [BackendType.VERTEX_AI, ['gemini-2.0-flash-exp']]
+  [BackendType.VERTEX_AI, ['gemini-2.0-flash-live-preview-04-09']]
 ]);
 
 /**

packages/ai/integration/live.test.ts

@@ -81,9 +81,6 @@ describe('Live', function () {
   };
 
   liveTestConfigs.forEach(testConfig => {
-    if (testConfig.ai.backend.backendType === BackendType.VERTEX_AI) {
-      return;
-    }
     describe(`${testConfig.toString()}`, () => {
       describe('Live', () => {
         it('should connect, send a message, receive a response, and close', async () => {