SCARBOROUGH — Scarborough is unlikely to expand a pilot food waste collection program based on preliminary results, while South Portland continues to test a similar program that has been well-received by its residents, officials say. Residential pickup service will be discontinued in Scarborough after its test program wrapped up earlier this month, but food waste will continue to be collected at several drop-off locations, Sustainability Coordinator Kerry Strout Grantham said. Scarborough and South Portland each launched food waste disposal programs in May.