Before he was a 22-year-old pop star capable of selling out two shows at TD Garden, Justin Bieber was a regular kid. And being Canadian — he was born and raised in Ontario — Bieber liked to play hockey. We talked to a woman this week who went to field hockey camp at Milton Academy in 2005, and she and her friends remember a towheaded pre-teen named Justin Bieber who was at hockey camp at Milton Academy at the same time. Though he was a reasonably talented skater, what the campers recall most about Bieber is, at night, he’d sing and play his guitar in the dorm, not something a lot of hockey players do. Of course, no one would have predicted then that within a few years, based on his YouTube videos, Bieber would become a big star. He still skates sometimes, but not often.