[native] Rename getAllMessages method

Summary:
The function changes in the next diff to return only a subset of messages from the thick threads.

https://linear.app/comm/issue/ENG-8699/store-only-non-pruned-messages-in-redux

Depends on D13106

Test Plan: Run the app on native and web and check if it opens correctly.

Reviewers: kamil, inka

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D13133