test: Avoid testing negative block heights

Summary:
This is a backport of core#24237

Depends on D12819

Test Plan:
With UBSAN
ninja && ninja check check-functional bitcoin-fuzzers

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12820