convert all remaining serializations to new style

Summary:
This converts all Bitcoin ABC serializations that were not converted by
Core backports.

Test Plan:
ninja all check-all

Build an avalanche proof with bitcoin-cli buildavalancheproof ... and verify the result hasn't changed.

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D9247