[accessibility]: start focus finding from a11y focus and reduce refocus on View.clearFocus

See go/android-a11y-sequential-focus-starting-point
for more details.

Flag: android.view.accessibility.a11y_sequential_focus_starting_point
Test: manual tests locally; see doc for further details.
Bug: 393668020
Change-Id: I701e376b5458ca012cb0f2a73e47f8fd1a0c19a4