Do not validate TTOR anymore

Summary: We can limit ourself to accept transaction in any order before the fork point.

Test Plan:

make check
./test/functional/test_runner.py -extended

Do full IBD

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: teamcity, Fabien, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2213