🐛 Fixed editor performance issues in Safari for posts with HTML or Markdown cards (#20806)

ref https://linear.app/tryghost/issue/ONC-261

- Previous method of hiding the second Lexical instance using `width:
0`, `height: 0`, and `overflow: hidden` caused CPU usage to spike,
likely due to CodeMirror continuously processing the element.

ghost/admin/app/components/koenig-lexical-editor.js

@@ -680,7 +680,7 @@ export default class KoenigLexicalEditor extends Component {
 
         const KGEditorComponent = ({isInitInstance}) => {
             return (
-                <div data-secondary-instance={isInitInstance ? true : false} style={isInitInstance ? {width: 0, height: 0, overflow: 'hidden'} : {}}>
+                <div data-secondary-instance={isInitInstance ? true : false} style={isInitInstance ? {display: 'none'} : {}}>
                     <KoenigComposer
                         editorResource={this.editorResource}
                         cardConfig={cardConfig}