Adding the new activity on the same TF of the cleared activity

While starting an activity with FLAG_ACTIVITY_CLEAR_TOP, the
existing activity could also be finished and therefore the new
activity is added on the same TF of the top running activity.
However, the top running activity could be on a TF which is
different from the cleared activity.

Bug: 233860721
Test: start Settings' shortcut activity
Test: atest TaskTests
Change-Id: I5607a2737e7d0d5986adf14f44f169791da3d38a