Data Inconsistency & Unexpected Structure Monitoring

[GalvinGao]

The latest activity in CN, opened last day (2022-05-01 16PM GMT+8) have empty DropInfos served on API for a whole 5 hours until a member @FlandiaYingman found such issue and informed us last night (2022-05-01 21PM GMT+8) and fixed in several minutes by manually purging the server-side cache. This has caused reports only starting from after 21PM GMT+8 and have caused some of the reports being flagged due to DropInfo mismatch.

In the future we should've been able to mitigate this by properly purging the cache after an update via Admin API have been performed (#58), but also we could add an additional end-to-end check via the real API on the soracli, so that consistency of API response is guaranteed. Further, this logic could've been abstracted and added to the server side too, creating autonomous monitoring tasks to continuously guard the service from serving dirty caches anymore in the future.