Fixes ActivityLifecycleTests flakiness

The Launcher Task has a empty child TaskFragment, which makes the
Launcher delayed to be paused and sometimes making lifecycle test
failed.

The direct child resumed activity should be paused immediately if
it shouldn't be stayed in the RESUMED state.

Bug: 329953510
Test: ActivityLifecycleTests
Test: TaskTests

Change-Id: I1a3331fd17f683896e39cc10b6e0f27fe76def0a