Update valid PSBT test vectors so that they properly use the value 0 for utxos's key

Summary: As per title, some of them still used 1, which stands for witness utxo that we do not support. However, due to unknown value being forwarded, it ended up working - but not testing what we expect.

Test Plan:

./test/functional/test_runner.py rpc_psbt.py

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D4498