Refactor: Use config.getGeminiClient() for GeminiClient instantiation (#715)

packages/cli/src/nonInteractiveCli.test.ts

@@ -51,6 +51,7 @@ describe('runNonInteractive', () => {
 
     mockConfig = {
       getToolRegistry: vi.fn().mockReturnValue(mockToolRegistry),
+      getGeminiClient: vi.fn().mockReturnValue(mockGeminiClient),
     } as unknown as Config;
 
     mockProcessStdoutWrite = vi.fn().mockImplementation(() => true);