feat(objectql,cli): backfillSummaryNulls accepts recomputeUndefinedOnEmpty — a just-declared min/max/avg roll-up can be filled on request (#15064)

feat(objectql,cli): backfillSummaryNulls accepts recomputeUndefinedOnEmpty — a just-declared min/max/avg roll-up can be filled on request (#15064) #7875