RecoveryManagerImpl should use Caffeine map

The RecoveryManagerImpl currently allows a user to configure the cache for holding in doubt transactions. The key and value both are not marshallable and thus the cache cannot be clustered or have persistence in any way. We should remove this configuration option and just create a Caffeine map that has lifespan set on the key.

Also the key can just be Xid as long as the RecoveryManager is scoped to a named cache.