[lib] Move test messages outside of the describe scope to reuse them

Summary:
Just moving the test messages outside of the sceop of the describe block so I can reuse them for the upcoming tests for the pinned messages

Depends on D9330

Resolves https://linear.app/comm/issue/ENG-5210/move-test-messages-outside-of-the-describe-scope-to-reuse-them

Test Plan: Ran flow and yarn workspace lib test

Reviewers: atul, ginsu

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9331