test: update custom dialog CSS in Lumo no-padding visual test (#9844)

Author: web-padawan

packages/dialog/test/visual/lumo/dialog.test.js

@@ -80,7 +80,7 @@ describe('dialog', () => {
   it('should not contain padding with no-padding theme', async () => {
     element.setAttribute('theme', 'no-padding');
     const contentStyles = new CSSStyleSheet();
-    contentStyles.insertRule('vaadin-dialog-overlay::part(content) { padding: 20px; }');
+    contentStyles.insertRule('vaadin-dialog::part(content) { padding: 20px; }');
     document.adoptedStyleSheets = [contentStyles];
     await nextUpdate(element);
     await visualDiff(div, 'content-no-padding-theme');