Defenceman Noah Dobson missed the first six games of the Canadiens’ first-round playoff series against the Tampa Bay Lightning because of a thumb injury. When Dobson played in Game 7 — which the Canadiens won 2-1 to take the best-of-seven series — Arber Xhekaj was made a healthy scratch. That didn’t really come as a surprise because head coach Martin St. Louis has a very short leash with Xhekaj. Canadiens defenceman Arber Xhekaj guards the front…