### 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

#include "amount.h"
#include "base58.h"
#include "chain.h"
#include "consensus/validation.h"
#include "core_io.h"
#include "httpserver.h"
#include "validation.h"
#include "net.h"
#include "policy/feerate.h"
#include "policy/fees.h"
#include "policy/policy.h"
#include "policy/rbf.h"
#include "rpc/mining.h"
#include "rpc/safemode.h"
#include "rpc/server.h"
#include "script/sign.h"
#include "timedata.h"
#include "util.h"
#include "utilmoneystr.h"
#include "wallet/coincontrol.h"
#include "wallet/feebumper.h"
#include "wallet/wallet.h"
#include "wallet/walletdb.h"
#include <init.h>  
#include <stdint.h>
#include <univalue.h>
static const std::string WALLET_ENDPOINT_BASE = "/wallet/";
CWallet *GetWalletForJSONRPCRequest(const JSONRPCRequest& request)