fix:修复预警计算记录链路逻辑错误

src/SJZY.Track.Application/Kafka/WarningCalcBackgroundService.cs

@@ -70,6 +70,7 @@ public sealed class WarningCalcBackgroundService : BackgroundService
         {
             _activity?.SetTag("HandleTime", _stopwatch.ElapsedMilliseconds);
             _activity?.Dispose();
+            _activity = null;
         }
     }
 
@@ -97,8 +98,6 @@ public sealed class WarningCalcBackgroundService : BackgroundService
 
         // 提交内存中所有的偏移到服务器，适用于EnableAutoCommit为false的手动提交场景
         _consumer.Commit();
-        _activity.Dispose();
-        _activity = null;
     }
 
     private async ValueTask MessageHandler(IEnumerable<Message<WarningSignalKey, WarningSignal>> messages, CancellationToken ct)