[native] Remove instances of LegacyThreadInfo throughout native
Summary:
Part of https://linear.app/comm/issue/ENG-6366/rename-minimallyencodedrawthreadinfo-to-rawthreadinfo
This diff addresses flow issues that arose in native as a result of D10670. There are more instances of this type that will be removed in subsequent diffs. This diff just gets us back to 0 flow issues.
Depends on D10671
Test Plan: flow, CI will run for this diff
Reviewers: ashoat, ginsu, tomek
Reviewed By: ashoat
Differential Revision: https://phab.comm.dev/D10672