fix: limit number of UTXOs retrieved with listunspent

This prevents the response from being too large and exceeding the 16MB
limit that we support.

Author: obycode

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

@@ -2599,6 +2599,9 @@ impl BitcoinRPCRequest {
         let min_conf = 0i64;
         let max_conf = 9999999i64;
         let minimum_amount = ParsedUTXO::sat_to_serialized_btc(minimum_sum_amount);
+        // Specify the maximum number of UTXOs to get from listunspent, to
+        // ensure the response is not too large.
+        let maximum_count = 1024;
 
         let payload = BitcoinRPCRequest {
             method: "listunspent".to_string(),
@@ -2607,7 +2610,7 @@ impl BitcoinRPCRequest {
                 max_conf.into(),
                 addresses.into(),
                 include_unsafe.into(),
-                json!({ "minimumAmount": minimum_amount }),
+                json!({ "minimumAmount": minimum_amount, "maximumCount": maximum_count }),
             ],
             id: "stacks".to_string(),
             jsonrpc: "2.0".to_string(),