curl -X DELETE 
--url http://localhost:6789/api/backfills/1
-H 'Content-Type: application/json' 
-H 'Cookie: oauth_token=some_really_long_string' 
-H 'X-API-KEY: zkWlN0PkIKSN0C11CfUHUj84OT5XOJ6tDZ6bDRO2' 
{
    "backfill": {
        "id": 1,
        "block_uuid": null,
        "completed_at": null,
        "created_at": "2023-07-17 21:48:42",
        "end_datetime": null,
        "failed_at": null,
        "interval_type": null,
        "interval_units": null,
        "metrics": null,
        "name": "arwen_starlight_backfill",
        "pipeline_schedule_id": null,
        "pipeline_uuid": "arwen_starlight",
        "start_datetime": null,
        "started_at": null,
        "status": null,
        "updated_at": "2023-07-17 21:48:42",
        "variables": null
    }
}

DELETE /api/backfills/:backfill_id