refactor: block import implies IsInitialBlockDownload
refactor: block import implies IsInitialBlockDownload

Former-commit-id: e274a97834020d086ff712979aeb98942223e94b
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin