lnd+walletunlocker: move history drop to unlocker

Apparently dropping the wallet transaction history only fully takes
effect after opening the wallet from scratch again. To do this cleanly,
we need to do it in the unlocker instead of lnd.

lnd.go

@@ -1146,6 +1146,7 @@ func waitForWalletPassword(cfg *Config, restEndpoints []net.Addr,
 	pwService := walletunlocker.New(
 		chainConfig.ChainDir, cfg.ActiveNetParams.Params,
 		!cfg.SyncFreelist, macaroonFiles, cfg.DB.Bolt.DBTimeout,
+		cfg.ResetWalletTransactions,
 	)
 
 	// Set up a new PasswordService, which will listen for passwords
@@ -1313,21 +1314,10 @@ func waitForWalletPassword(cfg *Config, restEndpoints []net.Addr,
 		// remind the user to turn off the setting again after
 		// successful completion.
 		if cfg.ResetWalletTransactions {
-			ltndLog.Warnf("Dropping all transaction history from " +
+			ltndLog.Warnf("Dropped all transaction history from " +
 				"on-chain wallet. Remember to disable " +
 				"reset-wallet-transactions flag for next " +
 				"start of lnd")
-
-			err := wallet.DropTransactionHistory(
-				unlockMsg.Wallet.Database(), true,
-			)
-			if err != nil {
-				if err := unlockMsg.UnloadWallet(); err != nil {
-					ltndLog.Errorf("Could not unload "+
-						"wallet: %v", err)
-				}
-				return nil, shutdown, err
-			}
 		}
 
 		return &WalletUnlockParams{