Fix Talkback should talk the strings in tutorial on the top screen

to guide user to exit one-handed mode.

Remove Tutorial view's LayoutParams.FLAG_NOT_TOUCHABLE
and FLAG_NOT_FOCUSABLE to enable Talkback talks.

Bug: 157121791

Test: manual
Test: atest SystemUITests
Change-Id: I36235fa839f33cc4f7aa73e07ae73b8e5880acbd