fix(性能测试): 修复在弹框中修改定时任务状态不生效的问题

--bug=1016782 --user=刘瑞斌 【性能测试】github #17904，定时任务配置页关闭定时任务后刷新页面定时任务变成开启状态 https://www.tapd.cn/55049933/s/1251868

Closes #17904

frontend/src/business/components/performance/test/EditPerformanceTest.vue

@@ -447,7 +447,6 @@ export default {
       });
     },
     saveCronExpression(cronExpression) {
-      this.test.schedule.enable = true;
       this.test.schedule.value = cronExpression;
       this.saveSchedule();
     },
@@ -466,6 +465,9 @@ export default {
       let url = '/performance/schedule/create';
       if (param.id) {
         url = '/performance/schedule/update';
+      } else {
+        // 创建定时任务，初始化是开启状态
+        this.test.schedule.enable = true;
       }
       this.$post(url, param, response => {
         this.$success(this.$t('commons.save_success'));