fix: use production parameter parent caches

[vmx]

In the C++ demo, the parent cache files didn't point to the parent caches
that match the production parameters (they depend on the PoRep ID).
Note that for 16KiB sectors, it isn't specified, hence I left the current value.

[sandsentinel]

Where can we obtain these new caches?

they depend on the PoRep ID

Is there a specific PoRep ID that we must use if we use these?

[vmx]

Where can we obtain these new caches?

You generate them. Usually when using the Filecoin proofs they are automatically generated if they don't exist yet. But you can also generate them with the gen_graph_cache tool. By default they are generated in /var/tmp/filecoin-parents, but you can change the output directory via the FIL_PROOFS_PARENT_CACHE env variable:

FIL_PROOFS_PARENT_CACHE=/dir/to/create/files/in cargo run --release --bin gen_graph_cache

There is also a list of the expected parameters checked in at https://github.com/filecoin-project/rust-fil-proofs/blob/2ec0a0fe4005a6f2f6659bbbc167a1d41ee855e0/storage-proofs-porep/parent_cache.json.

Is there a specific PoRep ID that we must use if we use these?

No, you only need to use the correct PoRep ID to generate them. The usage is independent of the PoRep ID. You can get the PoRep ID that corresponds to a certain proof version and sector size via RegisteredSealProof::porep_id().

[vmx]

With commit 199d8e2, only the 2KiB one is left to be updated.