### 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

{
    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(
            "getreceivedbyaddress \"address\" ( minconf )\n"
            "\nReturns the total amount received by the given address in transactions with at least minconf confirmations.\n"
            "\nArguments:\n"
            "1. \"address\"         (string, required) The bitcoin address for transactions.\n"
            "2. minconf             (numeric, optional, default=1) Only include transactions confirmed at least this many times.\n"
            "\nResult:\n"
            "amount   (numeric) The total amount in " + CURRENCY_UNIT + " received at this address.\n"
            "\nExamples:\n"
            "\nThe amount from transactions with at least 1 confirmation\n"
            + HelpExampleCli("getreceivedbyaddress", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\"") +
            "\nThe amount including unconfirmed transactions, zero confirmations\n"
            + HelpExampleCli("getreceivedbyaddress", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" 0") +
            "\nThe amount with at least 6 confirmations\n"
            + HelpExampleCli("getreceivedbyaddress", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" 6") +
            "\nAs a json rpc call\n"
            + HelpExampleRpc("getreceivedbyaddress", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", 6")