No, there is no need to 'scrape' the pads in preparation for the new rotors.
After replacing pads or rotors, you should always 'bed' or 'burnish' the new parts according to the pad manufacturer instructions. This process usually involves several hard stops from 50ish mph to get your rotors and pads up to temperature, then driving for ~10 minutes without touching the brakes to cool everything back down. The purpose of this procedure is to deposit a very thin, even layer of pad material onto the surface of the rotor, which allows the pads to grab onto the rotor much more consistently when the brake pedal is pressed - the process also aids in reducing pad noise.