Do not use obsoleted snapshot as staring window

We will use splash screen as starting window if the activity is in
finishing state. Now we will not use the activity with finishing
state to show the starting window, so we check the top activity
component to avoid using obsoleted snapshot as starting window.

Bug: 180893837
Test: atest ActivityStarterTests ActivityRecordTests
Change-Id: I27fb40d6d4e8808caf803ef78c39050258eab1a2