[native] Delete unused functions

Summary:
All the async functions that process a single store can now be deleted - we should only use the new function which processes all the stores in a single transaction.

https://linear.app/comm/issue/ENG-6004/wrap-all-store-operations-from-one-action-in-transaction

Depends on D11922

Test Plan: Checked if persisting drafts still works.

Reviewers: kamil, marcin, varun

Reviewed By: marcin

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11923