LAKE BUENA VISTA, Fla. — Their season saved for at least two more days, Boston coach Brad Stevens offered the most succinct assessment of his Celtics. “We’re prideful,” Stevens said. Celtic Pride. It was on display Friday night — when Jayson Tatum and his teammates announced very loudly that they’re not ready to see the world that exists outside the NBA’s restart bubble quite yet. Tatum had 31 points and 10 rebounds, Jaylen Brown added 28 points and the Celtics shook off a slow first half to top the Miami Heat 121-108 in Game 5 of the Eastern Conference finals and stave off elimination. “Our deal was to come out and play, come out and compete, give it our best shot and I thought we played pretty well in the second half,” Stevens said.