Rename function in bip65 integration test so it does not collide with create_transaction
Summary: Eliminate confusion while testing
Test Plan: Read it. This test is not passing at this time.
Reviewers: deadalnix, schancel, #bitcoin_abc, Fabien
Reviewed By: schancel, #bitcoin_abc, Fabien
Subscribers: teamcity, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D2069