Use correct input sequence for HTLC claims from counterparty commitments

Use correct input sequence for HTLC claims from counterparty commitments

HTLC outputs, like the `to_remote` output, in commitment transactions
with anchor outputs also have an additional `1 CSV` constraint on the
counterparty. When spending such outputs, their corresponding input
needs to have their sequence set to 1. This was done for HTLC claims
from holder commitments, but unfortunately not for counterparty
commitments as we were lacking test coverage.