In PR #3516 we have a new class TransactionResultSetFrame that abstracts over TransactionResultSet and TransactionResultSetV2 (the soroban-era TRS). At present, there's a flag V2_CONSUMERS_READY=false that causes all the V2-handling code to be disabled. This includes both the accumulation and hashing paths of TransactionResultSetFrame as well as the bottom of LedgerManagerImpl::applyTransactions where we call storeTransaction with -- currently -- the V1 XDR.

We need to figure out how to adapt everyone downstream to the V2 output before we switch over to it: both in meta and headers and also in checkpoint files emitted to the archives. This will therefore effect horizon and archivist, and also any catchup/replay machinery in core that depends on the presence of V1 checkpoints.