[lib] Deprecate minimallyEncodeRawThreadInfo

Summary:
We want to freeze existing logic for use in migration and rawThreadInfoFromServerThreadInfo while making it clear that it shouldn't be used in the future.

Depends on D12597

Test Plan: Just a rename.

Reviewers: ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12733