message: Bring spend tx back to value of spend serial records in sigma db
diff: @@ -314,7 +314,7 @@ void SigmaDatabase::RecordSpendSerial(
  auto serialData = SerializeSpendSerial(serial);
  auto keyData = CreateSpendSerialKey(propertyId, denomination, serialData);
  - AddEntry(GetSlice(keyData), leveldb::Slice(), height);
  + AddEntry(GetSlice(keyData), leveldb::Slice(std::string(spendTx.begin(), spendTx.end())), height);
  SpendAdded(propertyId, denomination, serial, spendTx);
  }
  