test: fix missing tx.hash -> tx.txid_hex and tx.sha256 -> tx.txid_int renamings
Summary: These occurences were missed in D18714, D18715 and D18716
Test Plan: run failing CI tests
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D18737