refactor(测试计划): 优化测试计划规划执行时的体验问题

--story=1006068 --user=刘瑞斌 测试计划页面，已存在的测试计划，点击规划执行，不展示“保存成功”提示 https://www.tapd.cn/55049933/s/1111630

frontend/src/business/components/track/plan/components/TestPlanEdit.vue

@@ -237,7 +237,9 @@ export default {
           }
           param.tags = this.form.tags;
           this.result = this.$post('/test/plan/' + this.operationType, param, response => {
-            this.$success(this.$t('commons.save_success'));
+            if (this.operationType === 'add') {
+              this.$success(this.$t('commons.save_success'));
+            }
             this.dialogFormVisible = false;
             this.$router.push('/track/plan/view/' + response.data.id);
           });