mulit: remove ListLeasedOutputs in LeaseOutput

This commit removes the call toe `ListLeasedOutputs` in `LeaseOutput` -
the returned info from `ListLeasedOutputs` can easily be accessed via
`FetchInputInfo` and this info is only used at one callsite.
`ListLeasedOutputs` then becomes unnecessary here, plus it's very slow
and needs to be refactored in `btcwallet` instead.

lnrpc/walletrpc/walletkit_server.go

@@ -490,7 +490,7 @@ func (w *WalletKit) LeaseOutput(ctx context.Context,
 	// other concurrent processes attempting to lease the same UTXO.
 	var expiration time.Time
 	err = w.cfg.CoinSelectionLocker.WithCoinSelectLock(func() error {
-		expiration, _, _, err = w.cfg.Wallet.LeaseOutput(
+		expiration, err = w.cfg.Wallet.LeaseOutput(
 			lockID, *op, duration,
 		)
 		return err