Use task display id when starting split screen

Before starting split screen animation, we dismiss the task view, which
can detach the clicked view immediately, if animations are dissabled.
That will cause NPE as view.getDisplay will be null

Bug: 138793362
Change-Id: I611f6a824f756eceeed57aac5afdf38f421ff8d2
diff --git a/quickstep/recents_ui_overrides/src/com/android/quickstep/TaskSystemShortcut.java b/quickstep/recents_ui_overrides/src/com/android/quickstep/TaskSystemShortcut.java
index 213c5d3..fd45923 100644
--- a/quickstep/recents_ui_overrides/src/com/android/quickstep/TaskSystemShortcut.java
+++ b/quickstep/recents_ui_overrides/src/com/android/quickstep/TaskSystemShortcut.java
@@ -207,8 +207,7 @@
                         }
                     };
                     WindowManagerWrapper.getInstance().overridePendingAppTransitionMultiThumbFuture(
-                            future, animStartedListener, mHandler, true /* scaleUp */,
-                            v.getDisplay().getDisplayId());
+                            future, animStartedListener, mHandler, true /* scaleUp */, displayId);
                 }
             });
         }