`RewindBlockIndex` was made to allow nodes upgrading to new consensus rules post-segwit fork to 
download new consensus data (i.e witnesses) without having to go through a whole IBD. It has been pointed than now really few pre-segwit nodes care to upgrade and that this logic may be irrelevant.

See https://github.com/bitcoin/bitcoin/pull/17737#discussion_r358514335 in review  of #17737 for more context pointers.
#endif
    node.chain_clients.clear();
    UnregisterAllValidationInterfaces();
    GetMainSignals().UnregisterBackgroundSignalScheduler();
    init::UnsetGlobals();
    node.mempool.reset();
    node.fee_estimator.reset();
    node.chainman = nullptr;
    node.scheduler.reset();
    try {
        if (!fs::remove(GetPidFile(*node.args))) {
            LogPrintf("%s: Unable to remove PID file: File does not exist\n", __func__);
        }
    } catch (const fs::filesystem_error& e) {
        LogPrintf("%s: Unable to remove PID file: %s\n", __func__, fsbridge::get_filesystem_error_message(e));
    }
    node.args = nullptr;
    LogPrintf("%s: done\n", __func__);
}
/**
 * Signal handlers are very limited in what they are allowed to do.
 * The execution context the handler is invoked in is not guaranteed,
 * so we restrict handler operations to just touching variables:
 */
#ifndef WIN32
static void HandleSIGTERM(int)
{
    StartShutdown();
}
static void HandleSIGHUP(int)