Requested by @andreimatei in #43032 (review)

Currently LeafTxnInputState and LeafTxnFinalState have an entire copy of the Transaction record. This is necessary: the structs should only contain the fields from the txn that can actually be updated by the leaf.

Andrei:

I think they are simply:
none from TxnMeta
Status
ObservedTimestamps

We can have the txn field too for backwards compatibility, but stop setting it based on a cluster version.