OffHeap size count doesn't work properly with VERSION or CUSTOM metadata

Off heap added a new getSize method on OffHeapEntryFactory. Unfortunately when using a VERSION or CUSTOM metadata we are adding 4 to the metadataSize instead of the offsetSize. This means that the value size is actually the metadata size on accident.

https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/container/offheap/OffHeapEntryFactoryImpl.java#L182