Cleanup graviton activation
Summary:
Move the graviton activation to use a block height and convert the
activation tests to be feature tests.
Depends on D4782.
Progress towards T653: Convert activation tests to feature tests.
Test Plan:
Run IBD.
ninja check ./test/functional/test_runner.py abc-minimaldata-activation abc-schnorrmultisig-activation
Reviewers: #bitcoin_abc, deadalnix, markblundeberg
Reviewed By: #bitcoin_abc, deadalnix, markblundeberg
Maniphest Tasks: T653
Differential Revision: https://reviews.bitcoinabc.org/D4642