✅(e2e) reduce flakiness in e2e tests

Flakiness in e2e tests has been reduced by:
- Adding waits for media-check processing in image tests.
- Ensuring that slash menu resets are handled
correctly to avoid flakiness.
- Wait for the Download button to be stable before clicking

src/frontend/apps/e2e/__tests__/app-impress/language.spec.ts

@@ -79,28 +79,19 @@ test.describe.serial('Language', () => {
   }) => {
     await createDoc(page, 'doc-toolbar', browserName, 1);
 
-    const header = page.locator('header').first();
     const editor = page.locator('.ProseMirror');
+
     // Trigger slash menu to show english menu
     await editor.click();
     await editor.fill('/');
     await expect(page.getByText('Headings', { exact: true })).toBeVisible();
-    await header.click();
-    await expect(page.getByText('Headings', { exact: true })).toBeHidden();
-
-    // Reset menu
-    await editor.click();
-    await editor.fill('');
 
     // Change language to French
     await waitForLanguageSwitch(page, TestLanguage.French);
 
     // Trigger slash menu to show french menu
-    await editor.click();
-    await editor.fill('/');
+    await editor.locator('.bn-block-outer').last().fill('/');
     await expect(page.getByText('Titres', { exact: true })).toBeVisible();
-    await header.click();
-    await expect(page.getByText('Titres', { exact: true })).toBeHidden();
   });
 });