fix: ensure that key register ops have change output

Author: obycode

testnet/stacks-node/src/burnchains/bitcoin_regtest_controller.rs

@@ -889,7 +889,7 @@ impl BitcoinRegtestController {
             fee_rate,
             &mut utxos,
             signer,
-            false,
+            true, // key register op requires change output to exist
         )?;
 
         increment_btc_ops_sent_counter();
@@ -1466,7 +1466,7 @@ impl BitcoinRegtestController {
             fee_rate,
             &mut utxos,
             signer,
-            true, // only block commit op requires change output to exist
+            true, // block commit op requires change output to exist
         )?;
 
         let serialized_tx = SerializedTx::new(tx.clone());