[lib] Add flow suppression to deprecatedDecodeMinimallyEncodedRawThreadInfo

Summary:
Add flow suppression in deprecatedDecodeMinimallyEncodedRawThreadInfo before call to decodeMinimallyEncodedMemberInfo.

This code path will only be encountered during legacy migrations where member permissions ARE persisted so flow "issues" aren't relevant going forward because deprecatedDecodeMinimallyEncodedRawThreadInfo should never be called anywhere new.

This gets us down to 2 flow issues, both with minimallyEncodeRawThreadInfo.

Depends on D12599

Test Plan: Close reading, there are no logic changes... just flow suppressions to account for differing representation of RawThreadInfo.members

Reviewers: ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12601