Enable parallel test execution for improved performance

Removed serial mode configuration to allow tests to run in parallel.
Tests now execute concurrently using 4 workers locally (2 in CI),
reducing overall execution time while maintaining stability.

All 5 tests passed successfully in parallel mode with no race conditions.

Author: mraible

e2e/tests/foundry.spec.ts

@@ -1,7 +1,5 @@
 import { test, expect } from '../src/fixtures';
 
-test.describe.configure({ mode: 'serial' });
-
 test.describe('Functions with Python - E2E Tests', () => {
   test('should render Hello UI extension', async ({ helloExtensionPage }) => {
     await helloExtensionPage.navigateToExtension();