refactor(性能测试): 测试报告统计展示median，字段名字更新

backend/src/main/java/io/metersphere/performance/base/Statistics.java

@@ -9,7 +9,7 @@ public class Statistics {
 
     private String samples;
 
-    private String ko;
+    private String fail;
 
     private String error;
 
@@ -19,6 +19,8 @@ public class Statistics {
 
     private String max;
 
+    private String median;
+
     private String tp90;
 
     private String tp95;

frontend/src/business/components/performance/report/components/RequestStatistics.vue

@@ -36,7 +36,7 @@
         />
 
         <el-table-column
-          prop="ko"
+          prop="fail"
           label="FAIL"
           align="center"
         />