修复响应时间断言添加不成功的bug

frontend/src/business/components/api/test/components/assertion/ApiAssertionResponseTime.vue

@@ -32,13 +32,12 @@
 
     methods: {
       add: function () {
-        this.remove();
         setTimeout(() => {
           this.duration.value = this.time;
         })
       },
       remove: function () {
-        this.duration.value = null;
+        this.duration.value = undefined;
       }
     }
   }

frontend/src/business/components/api/test/components/assertion/ApiAssertionsEdit.vue

@@ -13,7 +13,7 @@
       <div>
         {{$t("api_test.request.assertions.response_time")}}
       </div>
-      <ms-api-assertion-response-time :response-time="assertions.responseTime" :edit="true"/>
+      <ms-api-assertion-response-time :duration="assertions.duration" :edit="true"/>
     </div>
   </div>