The history tab would show an incorrect feerate for partial/unsigned (local) txs,
if they had any p2sh/p2wsh txins. We would just guess the script is p2wpkh, and
use that for the size calc. Now with calling add_info_from_wallet, the correct
size is used to calculate the feerate.
(The gui tx dialogs call add_info_from_wallet independently, so the size/feerate
shown there were already correct.)