MC-5810: Improve naming of the critical variables/parameters in the code and configuration

- Resolved pagebuilder panel failure

Author: Hwashiang Yu

app/code/Magento/PageBuilder/view/adminhtml/web/js/panel.js

@@ -237,7 +237,7 @@ export default class Panel {
                     _.map(
                         _.where(contentTypes, {
                             group: id,
-                            is_visible: true,
+                            is_system: true,
                         }), /* Retrieve content types with group id */
                         (contentType: ContentTypeConfigInterface, identifier: string) => {
                             return new GroupContentType(