[native] Update unshimClientDB to reflect best practices

Summary:
Noticed some issues while working on the web equivalent:

1. The operations are performed on SQLite but not applied to the local Redux store. As a result, the updated database won't be picked up until the next app restart. Figured it would be better to apply it immediately.
2. We were using custom logic instead of handleReduxMigrationFailure.

Depends on D11886

Test Plan: Tested the farcaster_mutual migration on a native client

Reviewers: tomek, kamil

Reviewed By: tomek

Differential Revision: https://phab.comm.dev/D11887