Defer dispatching task appeared until transition ready

So fillTaskInfo and onTaskAppeared will be called only once at
the surface placement after transition ready. It can also avoid
sending multiple task appeared event by the intermediate state.
Then the time to reach ITransitionPlayer#onTransitionReady may
be shorter.

Bug: 260059642
Test: TransitionTests#testRunningRemoteTransition
Test: OpenAppMicrobenchmark with shell transition.
Change-Id: I866189c327778f8c1e41de17326257bd1502b9b0