### 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

if (options.exists("subtractFeeFromOutputs"))
            subtractFeeFromOutputs = options["subtractFeeFromOutputs"].get_array();
        if (options.exists("replaceable")) {
            coinControl.signalRbf = options["replaceable"].get_bool();
        }
        if (options.exists("conf_target")) {
            if (options.exists("feeRate")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both conf_target and feeRate");
            }
            coinControl.m_confirm_target = ParseConfirmTarget(options["conf_target"]);
        }
        if (options.exists("estimate_mode")) {
            if (options.exists("feeRate")) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Cannot specify both estimate_mode and feeRate");
            }
            if (!FeeModeFromString(options["estimate_mode"].get_str(), coinControl.m_fee_mode)) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid estimate_mode parameter");
            }
        }
      }
    }
    
    CMutableTransaction tx;
    if (!DecodeHexTx(tx, request.params[0].get_str(), true))
        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
    if (tx.vout.size() == 0)
        throw JSONRPCError(RPC_INVALID_PARAMETER, "TX must have at least one output");
    if (changePosition != -1 && (changePosition < 0 || (unsigned int)changePosition > tx.vout.size()))
        throw JSONRPCError(RPC_INVALID_PARAMETER, "changePosition out of bounds");
    for (unsigned int idx = 0; idx < subtractFeeFromOutputs.size(); idx++) {