[Feature flag] Rollout `dingtalk_integration`

Summary

This issue is to rollout the feature on production, that is currently behind the dingtalk_integration feature flag.

Owners

• Team: Dev1
• Most appropriate slack channel to reach out to: #dev1
• Best individual to reach out to: @chaomao
• QA: @TomHeng
• PM: @lpeng1991
• EM: @daveliu

Todos

1. Enable production feature flag and check the feature(Need stay 2-3 days)
2. Remove the feature flag(Feature.remove(:feature_name))
3. Rollout the feature flag MR