fix(接口测试): 修复导入接口断言为空的缺陷

--bug=1025478 --user=王孝刚 【接口测试】导出api-再次导入到ms-断言数据全部缺失
https://www.tapd.cn/55049933/s/1363555

backend/src/main/java/io/metersphere/api/service/ApiDefinitionService.java

@@ -1223,7 +1223,6 @@ public class ApiDefinitionService {
             createCase = true;
         }
         msHTTPSamplerProxy.setId(apiDefinition.getId());
-        msHTTPSamplerProxy.setHashTree(new LinkedList<>());
         apiDefinition.setRequest(JSONObject.toJSONString(msHTTPSamplerProxy));
         return createCase;
     }
@@ -1242,7 +1241,6 @@ public class ApiDefinitionService {
             createCase = true;
         }
         tcpSampler.setId(apiDefinition.getId());
-        tcpSampler.setHashTree(new LinkedList<>());
         apiDefinition.setRequest(JSONObject.toJSONString(tcpSampler));
         return createCase;
     }