### 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 confirms = wtx.GetDepthInMainChain();
    entry.push_back(Pair("confirmations", confirms));
    if (wtx.IsCoinBase())
        entry.push_back(Pair("generated", true));
    if (confirms > 0)
    {
        entry.push_back(Pair("blockhash", wtx.hashBlock.GetHex()));
        entry.push_back(Pair("blockindex", wtx.nIndex));
        entry.push_back(Pair("blocktime", mapBlockIndex[wtx.hashBlock]->GetBlockTime()));
    } else {
        entry.push_back(Pair("trusted", wtx.IsTrusted()));
    }
    uint256 hash = wtx.GetHash();
    entry.push_back(Pair("txid", hash.GetHex()));
    UniValue conflicts(UniValue::VARR);
    for (const uint256& conflict : wtx.GetConflicts())
        conflicts.push_back(conflict.GetHex());
    entry.push_back(Pair("walletconflicts", conflicts));
    entry.push_back(Pair("time", wtx.GetTxTime()));
    entry.push_back(Pair("timereceived", (int64_t)wtx.nTimeReceived));
    
    std::string rbfStatus = "no";
    if (confirms <= 0) {
        LOCK(mempool.cs);
        RBFTransactionState rbfState = IsRBFOptIn(wtx, mempool);
        if (rbfState == RBF_TRANSACTIONSTATE_UNKNOWN)
            rbfStatus = "unknown";