MEMPHIS – The Knicks went back to collapsing. Ja Morant and the upstart Grizzlies ran rampant in the fourth quarter Friday night at FedEx Forum, recovering from a 15-point deficit overall and snapping the Knicks three-game winning streak, 118-114. Morant was the thrilling catalyst while scoring 15 of his 37 points in the final period, as the Knicks offense sputtered and stalled. Julius Randle scored 36 points for the visitors, but only six in the fourth quarter, when the Knicks succumbed to Memphis’ 36-18 run to end the game. It was a disheartening for the Knicks (28-39) to finish an otherwise…