Fix AI never casting paired commanders

forge-gui-desktop/src/test/java/forge/gamesimulationtests/util/PlayerControllerForTests.java

@@ -319,11 +319,6 @@ public class PlayerControllerForTests extends PlayerController {
         return true;
     }
 
-    @Override
-    public CardCollectionView getCardsToMulligan(Player firstPlayer) {
-        return null;
-    }
-
     @Override
     public void declareAttackers(Player attacker, Combat combat) {
         //Doing nothing is safe in most cases, but not all (creatures that must attack etc).  TODO: introduce checks?