[PiP2] Do not setFinishTaskTransaction in PiP2

PiP2's enter flow is different in that we resolve
TRANSIT_PIP's startWCT in Shell, and PipTransition
will always make sure to set the right alphas
at the start and finish.

Bug: 380030547
Flag: com.android.wm.shell.enable_pip2
Test: atest NexusLauncherOutOfProcTests:TaplTestsSplitscreen
Change-Id: I7d28ed5dcccecfab71ff324098d5c31653ce1c9f
diff --git a/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java b/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
index 95e7737..b4a4bfc 100644
--- a/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
+++ b/quickstep/src/com/android/quickstep/AbsSwipeUpHandler.java
@@ -152,10 +152,13 @@
 import com.android.systemui.shared.system.SysUiStatsLog;
 import com.android.systemui.shared.system.TaskStackChangeListener;
 import com.android.systemui.shared.system.TaskStackChangeListeners;
+import com.android.wm.shell.Flags;
 import com.android.wm.shell.shared.TransactionPool;
 import com.android.wm.shell.shared.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.shared.startingsurface.SplashScreenExitAnimationUtils;
 
+import kotlin.Unit;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -165,8 +168,6 @@
 import java.util.OptionalInt;
 import java.util.function.Consumer;
 
-import kotlin.Unit;
-
 /**
  * Handles the navigation gestures when Launcher is the default home activity.
  */
@@ -2176,8 +2177,9 @@
                     mSwipePipToHomeAnimator.getFinishTransaction(),
                     mSwipePipToHomeAnimator.getContentOverlay());
             mIsSwipingPipToHome = false;
-        } else if (mIsSwipeForSplit) {
+        } else if (mIsSwipeForSplit && !Flags.enablePip2()) {
             // Transaction to hide the task to avoid flicker for entering PiP from split-screen.
+            // Note: PiP2 handles entering differently, so skip if enable_pip2=true
             PictureInPictureSurfaceTransaction tx =
                     new PictureInPictureSurfaceTransaction.Builder()
                             .setAlpha(0f)