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.

lnwallet/chanfunding/assembler.go

@@ -44,7 +44,7 @@ type OutputLeaser interface {
 	// LeaseOutput leases a target output, rendering it unusable for coin
 	// selection.
 	LeaseOutput(i wtxmgr.LockID, o wire.OutPoint, d time.Duration) (
-		time.Time, []byte, btcutil.Amount, error)
+		time.Time, error)
 
 	// ReleaseOutput releases a target output, allowing it to be used for
 	// coin selection once again.

lnwallet/chanfunding/wallet_assembler.go

@@ -525,7 +525,7 @@ func (w *WalletAssembler) ProvisionChannel(r *Request) (Intent, error) {
 		for _, coin := range selectedCoins {
 			outpoint := coin.OutPoint
 
-			_, _, _, err = w.cfg.CoinLeaser.LeaseOutput(
+			_, err = w.cfg.CoinLeaser.LeaseOutput(
 				LndInternalLockID, outpoint,
 				DefaultReservationTimeout,
 			)