Merge #14926: test: consensus: Check that final transactions are valid

Summary:
PR14926 backport.

Pull request description:

There is no check that checks that final transactions are valid, i.e. the consensus rules could be changed (accidentally) with none of the tests failing.

Test Plan: ninja check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D5189