Make indication area visible when hub is showing

This change moves the logic which updates the visibility of the
indication area from the KeyguardIndicationController to the view
binder. It also ensures the indication area is visible when the hub is
showing.

Also refactored the view model unit test to follow current best
practices.

Bug: 340519071
Test: atest KeyguardIndicationAreaViewModelTest
Flag: EXEMPT refactor
Change-Id: I35f6c2251636cdaaae147e36a4e1a9c10cd6c03b