Disable zh as default locale when run upstream E2E tests in JH Pipeline

According to !384 (merged), which set zh_CN as default locale in JH, block some E2E test, so I want to propose another solution.

1. introduce JH only feature flag, enable by default, to make zh_CN as default locale
2. to remove env_test? method, make sure this feature flag is disabled by default in test runs. Some tests can enable it by adding enable_JH_locale tag in test definition.
3. when run upstream E2E test, use API to disable feature off by invoke REST API /api/features