[web-db] stop persisting drafts in redux-persist

Summary:
Drafts are now in SQLite - we can remove those from redux-persist (only for staff).

Depends on D7665

Test Plan: Check if drafts still works and are not persisted via redux-persist.

Reviewers: tomek, michal

Reviewed By: tomek

Subscribers: ashoat, atul

Differential Revision: https://phab.comm.dev/D7666