OKLAHOMA CITY — It’s no secret that the Lakers’ 3-point volume has dipped significantly since Luka Doncic has been sidelined with a left hamstring strain .  But if the Lakers are going to have any chance of beating the Thunder in their best-of-seven second-round playoff series, they’re going to have to reverse the trend regardless of Doncic’s status. The Lakers’ Austin Reaves (left) must attempt more 3-point shots to give LA a chance to defeat the Thunder. Getty Images The Lakers were a low-volume 3-point shooting team even before Doncic and Austin Reaves (left oblique) suffered their regular-season-ending injuries April 2 against the Thunder .  Just 36% of their shot attempts came from beyond the arc through April 2, according to Cleaning The Glass, which ranked 22nd among NBA teams. But Doncic, through his perimeter shooting and playmaking, helped the Lakers become a more threatening team from deep.…