Fix countries controller test
why we need this MR
Countries list do not contain JH_MARKET in upstream, but in JH, it contains JH_MARKET. Extract TestHelper to allow JH override assertion value.
JH MR
look this MR to get the whole picture, https://jihulab.com/gitlab-cn/gitlab/-/merge_requests/517
cc: @daveliu
Edited by MAO Chao