Don't include front most excluded task in Multi-Window mode

A front most excluded task is shown on Overview when changing font size
in Multi-Window mode. To fix this issue, RecentActivity should not reset
the config launch flags when it is restarted by configuration changes and
it should not reload the tasks which include a front most excluded task
when it is launched while docking a task.

Bug: 33031985
Test: manual - display app task excluded from Overview screen and then
               change font size in Multi-Window mode

Change-Id: Ic0c35cd06c14d9ed8d2dc46a01f2153738bad849