Mark TaskFragment transition ready after apply the transaction

Before, we would wait activity resume/pause to trigger setReady, which
can be timeout. Now, we call setAllReady after apply the transaction.

Fix: 267401674
Test: atest FlickerTests:OpenSecondaryToSplitTest
Change-Id: Icdf4ed8fda957b694644eed80dfc93b1314245e4