Cardi B sets a new record with “Backin’ It Up.” Cardi B now becomes the second woman ever to replace herself at No. 1 on the Billboard Mainstream R&B/Hip-Hop airplay chart as Pardison Fontaine’s “Backin’ It Up” track claims the top spot on the chart this week. Previously, the slot was held by Cardi’s “Money,” which now slides down to No. …