The Boston Celtics and Philadelphia 76ers are hours away from a do-or-die Game 7, and after initial reports that everyone on both teams was available, the Celtics have announced that they might be shorthanded on Saturday night.  Jayson Tatum , who was seen trying to work through some sort of left leg issue at the end of Game 7, has been downgraded to questionable for the game with left knee stiffness.  Celtics coach Joe Mazzulla held a conference call with the media on Friday and was insistent that Tatum was going to be available, but something clearly changed between Friday and Saturday afternoon. The Celtics did not hold a shoot around this morning.  Tatum left third quarter of Game 6 at his normal time, and never returned because the game was out of hand and Mazzulla decided to insert his bench. After the game, Tatum didn’t make much of the issue.  “You all probably saw when I went to the back, saw me on the bike,” he said after the loss.…