Update chainparams for 0.19.7 release
Update chainparams for 0.19.7 release

Summary:
Per release process.
Testnet has been updated in D3149, no need to update it again.

Test Plan:
  make check
Compare against your node

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D3171

Bitcoin-ABC/bitcoin-abc,cculianu/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,cculianu/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,cculianu/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,cculianu/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,cculianu/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,cculianu/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,cculianu/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,cculianu/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,ftrader-bitcoinabc/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc