Update chainparams for 0.19.5 release

Summary: Per release process. Testnet skipped due to continued reorgs on Schnorr testnet.

Test Plan:
make check
Compare against your own node's chainstate.

Reviewers: deadalnix, Fabien, Mengerian, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D2902