fix(性能测试): 修复创建性能测试偶发的保存后资源池被置空的问题

--bug=1026393 --user=宋天阳 【性能测试】创建测试-选择资源池保存/保存并执行-再次查看测试-资源池为空
https://www.tapd.cn/55049933/s/1376253

performance-test/frontend/src/business/test/components/PerformancePressureConfig.vue

@@ -396,10 +396,12 @@ export default {
         .then(response => {
           this.resourcePools = response.data;
           // 如果当前的资源池无效 设置 null
-          if (response.data.filter(p => p.id === this.resourcePool && p.performance).length === 0) {
+          if (this.resourcePool) {
-            this.resourcePool = null;
+            if (response.data.filter(p => p.id === this.resourcePool && p.performance).length === 0) {
-            // 标记因资源池无效而将资源池ID置为null
+              this.resourcePool = null;
-            this.setPoolNull = true;
+              // 标记因资源池无效而将资源池ID置为null
+              this.setPoolNull = true;
+            }
           }
 
           this.resourcePoolChange();