Part of https://linear.app/comm/issue/ENG-6366/rename-minimallyencodedrawthreadinfo-to-rawthreadinfo
RawThreadInfos looks like:
export type RawThreadInfos = { +[id: string]: LegacyRawThreadInfo | MinimallyEncodedRawThreadInfo, };
We want to remove as many instances as possible and narrow to MinimallyEncodedRawThreadInfos. MinimallyEncodedRawThreadInfos will eventually be renamed to RawThreadInfos
Depends on D10626