fix(场景导入): 修复导入har文件时覆盖的问题

--bug=1009820 --user=刘瑞斌 【接口测试】场景导入har格式，覆盖失败 https://www.tapd.cn/55049933/s/1096028

frontend/src/business/components/api/automation/scenario/common/ScenarioImport.vue

@@ -189,7 +189,10 @@
             break;
           }
         }
-      },
+        if (this.selectedPlatformValue === 'Har') {
+          this.formData.modeId = 'fullCoverage';
+        }
+      }
     },
     computed: {
       isHar() {