fix: return HTTP 429 - too many requests when rate limit reached

Author: ludomikula

server/api-service/lowcoder-sdk/src/main/java/org/lowcoder/sdk/exception/BizError.java

@@ -19,7 +19,7 @@ public enum BizError {
     INFRA_REDIS_TIMEOUT(500, 5006),
     INFRA_MONGO_TIMEOUT(500, 5007),
     INVALID_PERMISSION_OPERATION(500, 5008),
-    REQUEST_THROTTLED(500, 5009),
+    REQUEST_THROTTLED(429, 5009),
     SERVER_NOT_READY(503, 5010),
     REDIRECT(302, 5011),