Add feature flag rollout defaults for DRI, milestone, and due date

What does this MR do and why?

• Related issue: #373936
• Related comment: #373936 (comment 1103620996)

This MR adds feature flag rollout defaults for DRI, milestone, and due date.

We have some feature flags that have been enabled but have not removed for a long time. Also, we have some old feature flags that have not been enabled. With this change, we aim that these rollout issues will warn DRIs to complete the rollout phase of feature flags.