Do not notify transition finish for a initializing activity

Because startActivity always collects the launch activity to
transition participants, it may contain some records that are
not actual handled by transition.

For example, when launching activity under dream, because
dream activity has top z-order, the launching activity will
use mLaunchTaskBehind to be visible.
The z-order:
 Top TaskD DreamActivity
     TaskX B <-INITIALIZING
           A (Trampoline which launches B)
There might be a no-op transition triggered by A. If the
transition clears B's mLaunchTaskBehind, then after A is paused
B won't continue to resume.

Fix: 279647026
Test: TransitionTests#testIntermediateVisibility

Change-Id: Id0615c2bc6cbea1adb94e866db85567cdf514326