### 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

bool p2sh = true;
    if (!request.params[1].isNull()) {
        p2sh = request.params[1].get_bool();
    }
    Witnessifier w(pwallet);
    bool ret = boost::apply_visitor(w, dest);
    if (!ret) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Public key or redeemscript not known to wallet, or the key is uncompressed");
    }
    CScript witprogram = GetScriptForDestination(w.result);
    if (p2sh) {
        w.result = CScriptID(witprogram);
    }
    if (w.already_witness) {
        if (!(dest == w.result)) {
            throw JSONRPCError(RPC_WALLET_ERROR, "Cannot convert between witness address types");
        }
    } else {
        pwallet->AddCScript(witprogram);
        pwallet->SetAddressBook(w.result, "", "receive");
    }
    return EncodeDestination(w.result);
}
struct tallyitem
{
    CAmount nAmount;
    int nConf;
    std::vector<uint256> txids;
    bool fIsWatchonly;
    tallyitem()