Precompiled 2025-09-17-b2bafac

Convert index&document retention to use load_revision_pairs (#41040)

These were previously using `previous_revisions_of_documents` / `previous_revisions` (resp.) directly
(the latter only because `prev_ts` fields had not yet been sufficiently backfilled when this was last touched).
They can instead use `load_revision_pairs` and benefit from the pushed down join.

GitOrigin-RevId: 255135ef2a9b95484e94bb16da92dd7e0fcacf3d