[Lens] Show drag and drop options in the in-line editor (#215892)

## Summary

Closes https://github.com/elastic/kibana/issues/215441

Adds the euiYScroll styles only to the Lens Editor app, not to the Lens
in-line editor.

### Checklist

- [x] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

### Screen recording


https://github.com/user-attachments/assets/3e86bcb8-f79d-4b96-91f8-e04d53a510ad

x-pack/platform/plugins/shared/lens/public/editor_frame_service/editor_frame/config_panel/config_panel.tsx

@@ -6,7 +6,7 @@
  */
 
 import React, { useMemo, memo, useCallback } from 'react';
-import { EuiForm, euiBreakpoint, useEuiTheme } from '@elastic/eui';
+import { EuiForm, euiBreakpoint, useEuiTheme, useEuiOverflowScroll } from '@elastic/eui';
 import { ActionExecutionContext } from '@kbn/ui-actions-plugin/public';
 import { isOfAggregateQueryType } from '@kbn/es-query';
 import {
@@ -257,12 +257,12 @@ export function LayerPanels(
 
   return (
     <EuiForm
-      className="eui-yScroll"
       css={css`
         .lnsApp & {
           padding: ${euiTheme.size.base} ${euiTheme.size.base} ${euiTheme.size.xl}
             calc(400px + ${euiTheme.size.base});
           margin-left: -400px;
+          ${useEuiOverflowScroll('y')}
           ${euiBreakpoint(euiThemeContext, ['xs', 's', 'm'])} {
             padding-left: ${euiTheme.size.base};
             margin-left: 0;