Resolve #3322552 "Ckeditor5 support"

Closes #3322552

config/install/webform.settings.yml

@@ -197,8 +197,8 @@ element:
     password_confirm: password_confirm
 html_editor:
   disabled: false
-  element_format: ''
-  mail_format: ''
+  element_format: webform_default
+  mail_format: webform_default
   tidy: true
   make_unused_managed_files_temporary: true
 file: