ISPN-4681 Preloading from shared cachestore on a new node with non-share...

...d index is skipping indexing

https://issues.jboss.org/browse/ISPN-4681

This should solve ISPN-4048 and ISPN-4595 as well;  what it does is avoid indexing during preload in all cases except if we know for sure the index is not shareable (only ram falls into this category)
It's possible to have multiple indexes configured each one with its own provider. For example:
```
// Default is ram
hibernate.search.default.directory_provider=ram
// Person entities will go to infinispan directory
hibernate.search.Person.directory_provider=infinispan
// Car will be split into filesystem and ram
hibernate.search.Car.0.directory_provider=filesystem
hibernate.search.Car.1.directory_provider=ram
```