Fix finishing adjacent TaskFragments occludes activities below

Same as commit 33efd88, the TaskFragment without running activity
should be ignored while calculating activity visibility.

Bug: 200316506
Test: TaskFragmentOrganizerTest TaskFragmentOrganizerPolicyTest
Change-Id: Iad41edfb6055fff29360e6b4b543ff8ae724d2c3
1 file changed