### 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

"  \"fee\":       n,         (numeric) Fee in " + CURRENCY_UNIT + " the resulting transaction pays\n"
                            "  \"changepos\": n          (numeric) The position of the added change output, or -1\n"
                            "}\n"
                            "\nExamples:\n"
                            "\nCreate a transaction with no inputs\n"
                            + HelpExampleCli("createrawtransaction", "\"[]\" \"{\\\"myaddress\\\":0.01}\"") +
                            "\nAdd sufficient unsigned inputs to meet the output value\n"
                            + HelpExampleCli("fundrawtransaction", "\"rawtransactionhex\"") +
                            "\nSign the transaction\n"
                            + HelpExampleCli("signrawtransaction", "\"fundedtransactionhex\"") +
                            "\nSend the transaction\n"
                            + HelpExampleCli("sendrawtransaction", "\"signedtransactionhex\"")
                            );
    ObserveSafeMode();
    RPCTypeCheck(request.params, {UniValue::VSTR});
    CCoinControl coinControl;
    int changePosition = -1;
    bool lockUnspents = false;
    UniValue subtractFeeFromOutputs;
    std::set<int> setSubtractFeeFromOutputs;
    if (!request.params[1].isNull()) {
      if (request.params[1].type() == UniValue::VBOOL) {
        
        coinControl.fAllowWatchOnly = request.params[1].get_bool();
      }
      else {
        RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VOBJ});
        UniValue options = request.params[1];
        RPCTypeCheckObj(options,
            {