[Fix-7767]Task instance is not deleted while deleting the process instance (#7768)

* fix bug_7767

* fix bug_7767

* fix bug_7767

* fix bug_7767

* fix bug_7767

dolphinscheduler-api/src/main/java/org/apache/dolphinscheduler/api/service/impl/ProcessInstanceServiceImpl.java

@@ -632,6 +632,7 @@ public class ProcessInstanceServiceImpl extends BaseServiceImpl implements Proce
 
         processService.deleteAllSubWorkProcessByParentId(processInstanceId);
         processService.deleteWorkProcessMapByParentId(processInstanceId);
+        processService.deleteWorkTaskInstanceByProcessInstanceId(processInstanceId);
 
         if (delete > 0) {
             putMsg(result, Status.SUCCESS);

dolphinscheduler-service/src/main/java/org/apache/dolphinscheduler/service/process/ProcessService.java

@@ -529,6 +529,25 @@ public class ProcessService {
         }
     }
 
+    /**
+     * recursive delete all task instance by process instance id
+     * @param processInstanceId
+     */
+    public void deleteWorkTaskInstanceByProcessInstanceId(int processInstanceId) {
+        List<TaskInstance> taskInstanceList = findValidTaskListByProcessId(processInstanceId);
+        if (CollectionUtils.isEmpty(taskInstanceList)) {
+            return;
+        }
+
+        List<Integer> taskInstanceIdList = new ArrayList<>();
+
+        for (TaskInstance taskInstance : taskInstanceList) {
+            taskInstanceIdList.add(taskInstance.getId());
+        }
+
+        taskInstanceMapper.deleteBatchIds(taskInstanceIdList);
+    }
+
     /**
      * recursive query sub process definition id by parent id.
      *