[standardness] activate SCRIPT_VERIFY_INPUT_SIGCHECKS in next upgrade

Summary:
Just as a standardness rule, limit the per-input sigchecks.

https://github.com/bitcoincashorg/bitcoincash.org/pull/443

Test Plan:
ninja check-extended check-upgrade-activated-extended

Rerun ninja check-all with cmake .. -DBUILD_BITCOIN_WALLET=OFF.

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Maniphest Tasks: T704

Differential Revision: https://reviews.bitcoinabc.org/D5224