Always sign using replay protection

Summary: Now that the fork happened, we need to use replay protected transactions all the time. Doing otherwize will just create the opportunity to lose funds.

Test Plan:

make check
../qa/pull-tester/rpc-tests.py -extended

Reviewers: freetrader, CCulianu, #bitcoin_abc

Reviewed By: CCulianu, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D455