BlockHistoryScrubPlan

The plan block_history_scrub_survey renders (D10: the act consumes the same computation).

{
    "blocks": [
        {
            "block": "2521afcc-965b-4a33-b154-400abd5695f5",
            "chunks_to_empty": 0,
            "current_revision_flagged": true,
            "folded": true,
            "revisions_to_empty": 0
        }
    ],
    "cancels_ingest": true
}