`TestUserSecretAuditDiffRedaction` flakes when create and update audit
rows receive equal timestamps and `GetAuditLogsOffset` returns the tied
rows in either order.
Identify audit rows by action, or by diff content when both actions are
writes, instead of relying on slice position. Fixescoder/internal#1625.
Reviewed and updated by Coder Agents on behalf of @dylanhuff-at-coder.
dylanhuff-at-coder
952c0ce5e6