HSEARCH-1728 introduce new `metadata_writes_async` configuration property for Infinispan

 - https://hibernate.atlassian.net/browse/HSEARCH-1728

I did think the same ;-)
That was my first shot, but I've deleted it. It turned out of similarly complexity and it's equally as it would also rely on classnames and field methods.
With this solution at least the assertions will blow up on a very specific point, making it easier to fix in future.