wallet: additional patch for https://github.com/bitcoin/bitcoin/issues/20347
wallet: additional patch for https://github.com/bitcoin/bitcoin/issues/20347

How to review this PR:
  * Skim the description of https://github.com/bitcoin/bitcoin/issues/20347
    to see that it's roughly "when pick_new_inputs is unset but bnb_used is
    set, one the next iteration of the loop an assumption may be wrong"
  * See that in this case, we just add another iteration to the loop...
  * ...in exactly the same way as the other place that pick_new_inputs is
    turned off, I just missed this one before
  * Observe that the regression test fails before the patch but passes after.

ElementsProject/elements,ElementsProject/elements,ElementsProject/elements,ElementsProject/elements,ElementsProject/elements,ElementsProject/elements