减少离线考试事件类型

src/features/OfflineExam/OfflineExamList.vue

@@ -124,12 +124,7 @@ export default {
       this.$emit("reloadList");
     },
     previewPaper(course) {
-      window._hmt.push([
-        "_trackEvent",
-        "离线考试页面",
-        "预览",
-        course.courseName
-      ]);
+      window._hmt.push(["_trackEvent", "离线考试页面", "预览"]);
       var user = {
         loginName: course.examStudentId,
         backUrl: window.document.location.href,