Band-Aid is still getting mileage out of that jingle, too, and it’s a good thing it nabbed Manilow while it could. Around this same time, he’d written “Mandy,” which would soon hit No. 1 on the Billboard charts. The jingle-writing days were over.Reach for the SkaiSome celebrities are embarrassed by having had to do TV commercials on their way up fame’s ladder, but Skai Jackson isn’t one of them. In 2008, at just 8 years old, she sang the famous Band-Aid jingle while sitting in a sandbox. Earlier this year,…