add scrollable page check in sticky navigation test

apps/app/playwright/21-basic-features-for-guest/sticky-for-guest.spec.ts

@@ -5,6 +5,17 @@ test('Sub navigation sticky changes when scrolling down and up', async ({
 }) => {
   await page.goto('/Sandbox');
 
+  // Wait until the page is scrollable
+  await expect
+    .poll(async () => {
+      const { scrollHeight, innerHeight } = await page.evaluate(() => ({
+        scrollHeight: document.body.scrollHeight,
+        innerHeight: window.innerHeight,
+      }));
+      return scrollHeight > innerHeight + 250;
+    })
+    .toBe(true);
+
   // Sticky
   await page.evaluate(() => window.scrollTo(0, 250));
   await expect(page.locator('.sticky-outer-wrapper').first()).toHaveClass(