CLAP-390 Fix: 종료에서 완료로 상태변경시 종료일 초기화 되는 문제 수정

Author: parkjaehak

src/main/java/clap/server/domain/model/task/Task.java

@@ -69,10 +69,9 @@ public void finalSave(int attachmentCount) {
     }
 
     public void updateTaskStatus(TaskStatus status) {
-        if (status.equals(TaskStatus.COMPLETED)) {
+        if (TaskStatus.COMPLETED.equals(status)) {
             this.finishedAt = LocalDateTime.now();
-        }
-        if (this.taskStatus == TaskStatus.TERMINATED || this.taskStatus == TaskStatus.COMPLETED) {
+        } else if (TaskStatus.TERMINATED.equals(this.taskStatus) || TaskStatus.COMPLETED.equals(this.taskStatus)) {
             this.finishedAt = null;
         }
         this.taskStatus = status;