We currently expect the already-siloed hash. This currently matches private-land.
The reason we're doing this in private is because of a weirdness in the protocol.
In particular, we silo by contract address before we silo by note nonce for uniqueness. That will change eventually, and the function will accept the unique unsiloed note hash (siloed by nonce, but not by contract address), and will then silo and pass to the DB function
Basically once we swap ordering of silo hashing and uniqueness hashing, user code can provide unique note hashes when submitting existence check requests to then be siloed by the protocol.
We currently expect the already-siloed hash. This currently matches private-land.
checkNoteHashExists