Call Wallet::cancel_tx for temporary transactions

We create temporary transactions for fee estimation purposes. Doing this might
advance the descriptor state though. So here we call `cancel_tx` to tell
the wallet we no longer intend to broadcast the temporary transactions.

Author: tnull

src/wallet/mod.rs

@@ -404,6 +404,10 @@ where
 								);
 								e
 							})?;
+
+						// 'cancel' the transaction to free up any used change addresses
+						locked_wallet.cancel_tx(&tmp_tx);
+
 						let estimated_spendable_amount = Amount::from_sat(
 							spendable_amount_sats.saturating_sub(estimated_tx_fee.to_sat()),
 						);