### Describe the issue

I added a second new wallet2.dat. Now I wanted to encrypt it, but `bitcoin-cli help` does not show the command to do so, I need to use `bitcoin-cli -rpcwallet=wallet2.dat help`. This is very un-intuitive, and bad for a help function.

### Can you reliably reproduce the issue?

1. have an encrypted default wallet
2. add new multi wallet wallet2.dat via config file or cmd line options
3. naive `bitcoin-cli help` does not show command to encrypt second wallet.

### Expected behaviour

All wallet encryption, lock and unlock commands should be shown unconditionally in `bitcoin-cli help`.

The dynamic hiding of some lines is arguably worse than the benefit with multiple wallets.

### Actual behaviour

`bitcoin-cli help` shows only wallet encryption commands appropriate for the default wallet.

### What version of bitcoin-core are you using?

bitcoind 0.15.0.1~dfsg-1
deb http://ppa.launchpad.net/luke-jr/bitcoin-core-bip148-unofficial-builds/ubuntu zesty main

### Machine specs:
- OS: Debian 9.2

int pos = subtractFeeFromOutputs[idx].get_int();
        if (setSubtractFeeFromOutputs.count(pos))
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, duplicated position: %d", pos));
        if (pos < 0)
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, negative position: %d", pos));
        if (pos >= int(tx.vout.size()))
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid parameter, position too large: %d", pos));
        setSubtractFeeFromOutputs.insert(pos);
    }
    CAmount nFeeOut;
    std::string strFailReason;
    if (!pwallet->FundTransaction(tx, nFeeOut, changePosition, strFailReason, lockUnspents, setSubtractFeeFromOutputs, coinControl)) {
        throw JSONRPCError(RPC_WALLET_ERROR, strFailReason);
    }
    UniValue result(UniValue::VOBJ);
    result.push_back(Pair("hex", EncodeHexTx(tx)));
    result.push_back(Pair("changepos", changePosition));
    result.push_back(Pair("fee", ValueFromAmount(nFeeOut)));
    return result;
}
UniValue bumpfee(const JSONRPCRequest& request)
{
    CWallet * const pwallet = GetWalletForJSONRPCRequest(request);
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp))
        return NullUniValue;
    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2) {
        throw std::runtime_error(
            "bumpfee \"txid\" ( options ) \n"
            "\nBumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.\n"
            "An opt-in RBF transaction with the given txid must be in the wallet.\n"