fix(测试跟踪): 没有缺陷的时候点击同步会一直显示同步中

--bug=1019986 --user=陈建星 【测试跟踪】开源版-缺陷管理-同步禅道缺陷-一直处于加载状态+github#19856 https://www.tapd.cn/55049933/s/1300005

test-track/backend/src/main/java/io/metersphere/service/IssuesService.java

@@ -942,6 +942,7 @@ public class IssuesService {
             List<IssuesDao> issues = extIssuesMapper.getIssueForSync(projectId, project.getPlatform());
 
             if (CollectionUtils.isEmpty(issues)) {
+                deleteSyncKey(projectId);
                 return true;
             }