Use INX listen_to_treasury_updates instead of blocks.rs

[grtlr]

This should be cleaner and better for performance because we don't have to filter over all Blocks of a milestone. It would probably be best to do something similar like we do with the ledger updates:

cx.add_stream(LedgerUpdateStream::new(
    inx.listen_to_ledger_updates((start_index.0..).into()).await?,
));

[grtlr]

We are waiting for a decision on the future of the Treasury output.

[DaughterOfMars]

Still waiting.