fix(测试用例): 修复测试用例自定义字段有重复的问题

backend/src/main/java/io/metersphere/service/CustomFieldService.java

@@ -135,7 +135,7 @@ public class CustomFieldService {
                 result.add(customFieldDao);
             });
         }
-        return result;
+        return result.stream().distinct().collect(Collectors.toList());
     }
 
     public List<CustomField> getFieldByIds(List<String> ids) {