Remove MutinyStatelessSessionDelegator#upsert(String entityName, Object entity) method (#2246)

Author: dreab8

hibernate-reactive-core/src/main/java/org/hibernate/reactive/mutiny/delegation/MutinyStatelessSessionDelegator.java

@@ -211,11 +211,6 @@ public <T> Uni<T> fetch(T association) {
         return delegate().fetch(association);
     }
 
-    @Incubating
-    public Uni<Void> upsert(String entityName, Object entity) {
-        return delegate().upsert(entityName, entity);
-    }
-
     @Incubating
     public Uni<Void> upsertAll(Object... entities) {
         return delegate().upsertAll(entities);