Not possible to migrate 11.x SFS stores when custom marshaller used

When upgrading a SFS cache from Infinipan 11.x -> 12.1.x, on initial startup, the contents of the SFS store are migrated so that they are compatible with the 12.1.x marshalling. However, the `migrateFromV11` method will always fail when a custom marshaller is configured. This is due to the old loadLegacyObject implementation always attempting to read from the user marshaller first and only catching IllegalArgumentException before retring with the persistence marshaller.

The need to migrate data between 11.x and 12.1.x formats was caused by ISPN-11614, however this does not affect the compatibility of custom marshaller bytes as the persistence marshaller already wrapped custom marshaller key/values in a MarshallableUserObject.