Mark the task as reusable while clearing activities in the Task

All activities above the task root activity in the Task were
finished while starting an Activity that declared with
android:clearTaskOnLaunch=true. In that case, the organizer
removed the secondary TaskFragment since the TaskFragment was
empty. The primary TaskFragment was also removed due to the
finish-primary-with-secondary rule.

Bug: 257559481
Test: repo steps on the bug
Change-Id: I52c019a8c550d6402916f7ae4499fb7692ff04f1