[native] Deprecate socket crash loop recovery specialized to policy acknowledgment

Summary:
We used to have a special way to recover from a socket crash loop that results from policy acknowledgment.

Now that we have a more general way to recover from a socket crash loop, we can deprecate this old code, and rely on the more general mechanism going forward.

Test Plan:
I was inspired by @kamil's test plan in D6250:

1. Log out a test user
2. DELETE FROM policy_acknowledgments WHERE user = '<userID>';
3. Apply this single-line patch to force the keyserver to timeout all socket initializations: https://gist.github.com/Ashoat/c5d2d81dcb8517595f28fdff6604daa9
4. Log in as the test user
5. Confirm that we can heal from the simulated crash loop via fetch_pending_updates

Reviewers: kamil

Reviewed By: kamil

Subscribers: tomek, kamil

Differential Revision: https://phab.comm.dev/D12386