### 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

entry.push_back(Pair("category", "receive"));
                }
                entry.push_back(Pair("amount", ValueFromAmount(r.amount)));
                if (pwallet->mapAddressBook.count(r.destination)) {
                    entry.push_back(Pair("label", account));
                }
                entry.push_back(Pair("vout", r.vout));
                if (fLong)
                    WalletTxToJSON(wtx, entry);
                ret.push_back(entry);
            }
        }
    }
}
void AcentryToJSON(const CAccountingEntry& acentry, const std::string& strAccount, UniValue& ret)
{
    bool fAllAccounts = (strAccount == std::string("*"));
    if (fAllAccounts || acentry.strAccount == strAccount)
    {
        UniValue entry(UniValue::VOBJ);
        entry.push_back(Pair("account", acentry.strAccount));
        entry.push_back(Pair("category", "move"));
        entry.push_back(Pair("time", acentry.nTime));
        entry.push_back(Pair("amount", ValueFromAmount(acentry.nCreditDebit)));
        entry.push_back(Pair("otheraccount", acentry.strOtherAccount));
        entry.push_back(Pair("comment", acentry.strComment));
        ret.push_back(entry);
    }
}
UniValue listtransactions(const JSONRPCRequest& request)