The previous tests patched google_auth_httplib2 and googleapiclient which
no longer exist in the new implementation. Rewrite to mock AuthorizedSession
and _upload_aab_resumable, covering the same scenarios: happy path, retry
on transient errors, backoff delays, and exhausted attempts.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>