Persistent state transfer and purge on startup warning should not be produced for cache loaders only (not store)

Warning messages such as this should not appear when the cache loader is read only, i.e. ClusterCacheLoader:
2012-03-01 22:27:34,523 | ISPN000149: Fetch persistent state and purge on startup are both disabled, cache may contain stale entries on startup

The original warning message came from ConfigurationValidatingVisitor where there was, a check to see if the cache loader was really a cache store (i.e. loaderConfig instanceof CacheStoreConfig). This is not present in LoaderConfigurationBuilder for the new configuration style.

So, add it to LoaderConfigurationBuilder and mark ConfigurationValidatingVisitor as deprecated.