Also put show in the finish transaction when setting up animation

It's possible for a series of merges to happen on the same task.
If only the hide's are represented in the finishT and the startTs
were merged, then its possible to leave surfaces hidden when
they shouldn't be.

Bug: 278590171
Test: make rapid successive quickswitches and swipe-ups.
Change-Id: Ifacf5811cb64451013df87f7305f761c5eb78a47

libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java

@@ -429,6 +429,7 @@ public class Transitions implements RemoteCallable<Transitions> {
                         && (change.getFlags() & FLAG_STARTING_WINDOW_TRANSFER_RECIPIENT) == 0) {
                     t.setAlpha(leash, 0.f);
                 }
+                finishT.show(leash);
             } else if (mode == TRANSIT_CLOSE || mode == TRANSIT_TO_BACK) {
                 finishT.hide(leash);
             }