`StoreId` should be passed as Chunk metadata

[teh-cmc]

We currently pass the StoreId in the serde/msgpack layer.

We should use the Chunk's metadata for this. This is a pre-requisite for having a fully standardized data ingestion API.

• Requires Chunk metadata should be passed as an outer container #6572 first so we don't store that ID a million times in the chunk store.

Update: same is true for timepoint_max etc.