Recents scroll backwards (accessibility) if clear all button invisible

Currently accessibility prevents swiping from node to node will not show
the "clear all" button when scrolling backwards. Changing the logic to
check the visiblity of the "clear all button" will allow it to be
focusable when invisible and scrolling past the first task.

Bug: 37005488
Test: start Talkback, populate with apps, swipe left continuous past the
first task item
Change-Id: I1733382e62fc72b19ca6a074aa96adf4c0c8b178