Make keyguard binders update their own views

The modified binder classes (among other things) are binding an alpha
value to their views. Previously they were changing the alpha value of
their own views, but setting the accessibility flags on the root view
that is injected to them.
This was sometimes leading into marking the NotificationShadeWindowView as
IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS, which lead to skipping
refreshing the accessibility node cache, which lead to flaky or failing
integration tests.

Fixes: 294229320
Bug: 257543607
Test: execute Notification integration tests
Change-Id: Iff9a2865187b2ecbba92b7cf992fdcdbb3e2993e