Consider tasks with INVALID_DISPLAY as it's on DEFAULT_DISPLAY

- In the test environment, some main display tasks can have INVALID_DISPLAY (-1) as their displayId, we should consider them as main display tasks or else they'll be sorted to an unexpected section in RecentsView

Bug: 391311008
Test: TaplTestsQuickstep#testQuickSwitchFromHome
Flag: com.android.launcher3.enable_separate_external_display_tasks
Change-Id: I5a89d91e342557e114eae6796e153a160d729301