remove unneeded setRollExpression on the renderer (#337)

Author: Rachael-E

src/main/java/com/esri/samples/scene/orbit_the_camera_around_an_object/OrbitTheCameraAroundAnObjectController.java

@@ -79,7 +79,6 @@ public void initialize() {
       SimpleRenderer renderer = new SimpleRenderer();
       renderer.getSceneProperties().setHeadingExpression("[HEADING]");
       renderer.getSceneProperties().setPitchExpression("[PITCH]");
-      renderer.getSceneProperties().setRollExpression("[ROLL]");
       sceneGraphicsOverlay.setRenderer(renderer);
 
       // create a graphic of a plane model