Remove demo from readme as users can create free trial on production (#9952)

We have recently introduced the possibility to sign up on Twenty cloud
without having to input a credit card which makes the demo.twenty.com
useless. Deprecating it!

packages/twenty-e2e-testing/tests/login.setup.ts

@@ -19,7 +19,7 @@ test('Login test', async ({ loginPage, page }) => {
     async () => {
       await page.waitForLoadState('networkidle');
       if (
-        page.url().includes('demo.twenty.com') ||
+        page.url().includes('app.twenty-next.com') ||
         !page.url().includes('app.localhost:3001')
       ) {
         await loginPage.clickLoginWithEmail();