feat: Removed spec code to change theme

Author: lamATnginx

tests/src/visual-regression.spec.js

@@ -6,11 +6,6 @@ test.describe('Testing old theme', () => {
   }) => {
     const currentPlus = 'nginx/installing-nginx-open-source/';
     await page.goto(`/${currentPlus}`, { waitUntil: 'networkidle' });
-    await page.evaluate(() => {
-      // switch to old theme
-      useNewTheme(false);
-      window.scrollTo(0, 0);
-    });
     await page.waitForFunction(() => window.scrollY === 0);
     await expect(page).toHaveScreenshot('example-site-screenshot.png', {
       fullPage: true,