scripted-diff: Use generate* from TestFramework
Summary:
Backport of core#22788.
Depends on D12477.
Test Plan:
ninja check-functional-extended
Reviewers: #bitcoin_abc, PiRK
Reviewed By: #bitcoin_abc, PiRK
Subscribers: PiRK
Differential Revision: https://reviews.bitcoinabc.org/D12478