`banlist.dat` was introduced in https://github.com/bitcoin/bitcoin/pull/6310, storing nodes that were automatically banned (due to exceeding the misbehavior threshold) and manually banned (through the `setban` RPC).

Automatic bans were removed in https://github.com/bitcoin/bitcoin/pull/19219 and replaced with a discouragement filter. That filter is not saved to disk/persisted over shutdown/startup. The `banlist.dat` therefore now only contains addresses that have been banned through the `setban` rpc.

Since https://github.com/bitcoin/bitcoin/pull/15935, we have a specific file for configuration that is updated through the RPC and persisted over shutdown/startup, namely `settings.json`. We should therefore move the manual ban configuration from `banlist.dat` to `settings.json`. Doing so has a couple of benefits:

- `settings.json` is human readable and easily analyzable by any json parser.
- we wouldn't need to maintain custom [de]serialization code for the `banlist.dat` file.

`banlist.dat` is expected to be fairly small and infrequently updated, so disk space/performance are not huge concerns.
if (args.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY)) {
        if (args.SoftSetBoolArg("-whitelistrelay", false))
            LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting -whitelistrelay=0\n", __func__);
    }
    
    if (args.GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
        if (args.SoftSetBoolArg("-whitelistrelay", true))
            LogPrintf("%s: parameter interaction: -whitelistforcerelay=1 -> setting -whitelistrelay=1\n", __func__);
    }
}
/**
 * Initialize global loggers.
 *
 * Note that this is called very early in the process lifetime, so you should be
 * careful about what global state you rely on here.
 */
void InitLogging(const ArgsManager& args)
{
    init::SetLoggingOptions(args);
    init::LogPackageVersion();
}
namespace { 
int nMaxConnections;
int nUserMaxConnections;
int nFD;
ServiceFlags nLocalServices = ServiceFlags(NODE_NETWORK | NODE_NETWORK_LIMITED);
int64_t peer_connect_timeout;
std::set<BlockFilterType> g_enabled_filter_types;
} 
[[noreturn]] static void new_handler_terminate()