Fix the assumevalid test failure

Summary:
There is a pad_tx missing for the transaction in block 102. Starting
anomaly to block 0 for regtest in D2318 made it appear.

Test Plan:

./test/functional/test_runner.py assumevalid

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2386