lnd: revert back to prior default wallet public passphrase

In this commit we ensure the behavior of lnd with the —noencryptwallet
command line option heaves as it did before user initiated wallet
encryption was implemented. We do this by modifying the
waitForWalletPassword method to instead return two pass phrases: one
public and one private. The default wallet public passphrase is then
restarted back to the value which was used stoically in the codebase
before the latest merged PR.

chainregistry.go

@@ -103,7 +103,8 @@ type chainControl struct {
 // branches of chainControl instances exist: one backed by a running btcd
 // full-node, and the other backed by a running neutrino light client instance.
 func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
-	walletPw []byte) (*chainControl, func(), error) {
+	privateWalletPw, publicWalletPw []byte) (*chainControl, func(), error) {
+
 	// Set the RPC config from the "home" chain. Multi-chain isn't yet
 	// active, so we'll restrict usage to a particular chain for now.
 	homeChainConfig := cfg.Bitcoin
@@ -132,8 +133,8 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 	}
 
 	walletConfig := &btcwallet.Config{
-		PrivatePass:  walletPw,
-		PublicPass:   walletPw,
+		PrivatePass:  privateWalletPw,
+		PublicPass:   publicWalletPw,
 		DataDir:      homeChainConfig.ChainDir,
 		NetParams:    activeNetParams.Params,
 		FeeEstimator: cc.feeEstimator,