feat: update Lumo scroller to also add new overflow variants

Author: web-padawan

packages/scroller/test/visual/base/screenshots/scroller/baseline/theme-overflow-indicators-both.png

@@ -4,7 +4,7 @@ import { css, registerStyles } from '@vaadin/vaadin-themable-mixin/vaadin-themab
 registerStyles(
   'vaadin-scroller',
   css`
-    :host([theme~='overflow-indicators'])::-webkit-scrollbar {
+    :host([theme*='overflow-indicator'])::-webkit-scrollbar {
       display: none;
     }
   `,

packages/scroller/test/visual/hide-scrollbar.js

@@ -33,7 +33,7 @@ describe('scroller', () => {
   });
 
   it('theme-overflow-indicators-bottom', async () => {
-    element.setAttribute('theme', 'overflow-indicators');
+    element.setAttribute('theme', 'overflow-indicator-bottom');
     await visualDiff(div, 'theme-overflow-indicators-bottom');
   });
 
@@ -44,7 +44,7 @@ describe('scroller', () => {
   });
 
   it('theme-overflow-indicators-top', async () => {
-    element.setAttribute('theme', 'overflow-indicators');
+    element.setAttribute('theme', 'overflow-indicator-top');
     element.scrollTop = element.scrollHeight - element.clientHeight;
     await visualDiff(div, 'theme-overflow-indicators-top');
   });

packages/scroller/test/visual/lumo/screenshots/scroller/baseline/theme-overflow-indicators-both.png

@@ -14,8 +14,8 @@
     box-shadow: 0 0 0 var(--_focus-ring-width) var(--_focus-ring-color);
   }
 
-  :host([theme~='overflow-indicators'])::before,
-  :host([theme~='overflow-indicators'])::after {
+  :host([theme*='overflow-indicator'])::before,
+  :host([theme*='overflow-indicator'])::after {
     background: var(--lumo-contrast-10pct);
   }
 }