Create login.js to check for fallback login route

packages/volto/cypress/tests/coresandbox/login.js

@@ -0,0 +1,17 @@
+import { ploneAuth } from '../../support/constants';
+
+describe('Login Tests', () => {
+  beforeEach(() => {
+    cy.visit('/fallback_login');
+  });
+  it('Check login redirect when the login is at another root', function () {
+    const user = ploneAuth[0];
+    const password = ploneAuth[1];
+
+    cy.get('#login').type(user).should('have.value', user);
+    cy.get('#password').type(password).should('have.value', password);
+    cy.get('#login-form-submit').click();
+    cy.wait(3000);
+    cy.location('pathname').should('eq', '/');
+  });
+});