fix: 修复 getJsonString 缺失闭合括号，删除未使用的 helper

haha-service/src/main/java/com/haha/service/payment/payscore/impl/WxPayScoreStrategy.java

@@ -781,26 +781,8 @@ public class WxPayScoreStrategy implements PayScoreStrategy {
             return json.get(key).asText();
         }
         return null;
-
-    /**
-     * 从 MalformedMessageException 中提取 JSON 响应体
-     * SDK 的 String.class 反序列化会抛此异常，响应体在异常消息中
-     */
-    private JsonNode parseResponseFromException(MalformedMessageException e) throws Exception {
-        String message = e.getMessage();
-        if (message != null) {
-            int start = message.indexOf("{");
-            int end = message.lastIndexOf("}");
-            if (start >= 0 && end > start) {
-                String body = message.substring(start, end + 1);
-                log.info("[微信支付分] 从异常中提取响应体: {}", body);
-                return objectMapper.readTree(body);
-            }
-        }
-        throw e;
     }
 
-
     /**
      * 解析支付时间
      */