Broken `query_tx_deltas`

[grarco]

I believe there's an issue with query_tx_deltas. https://github.com/anoma/namada/blob/50caebb38c07fb43dbf102e3817eafd4ffd693fd/sdk/src/masp.rs#L1909

The function relies on calling tx_search which is only available if the node has indexing turned on (which we disable by default given the increase in storage consumption).

Even if the indexer is indeed available, the function produces a query based on the attributes transfer.source, transfer.target, transfer.token, but we never actually produce these attributes in finalize_block. Indeed, from some tests I ran, the query always returns an empty response.