Improve clear a11y forcus for A11yManagerService

Clear a11y focus needs to find focused a11y node, and
perform clear a11y focus action in a11y client. It takes
2 binder calls and needs to wait for result in each call.

This patch combines two actions, and skip waiting block to
improve stability problem.

Bug: 109719681
Test: atest CtsAccessibilityServiceTestCases
Test: atest AccessibilityInteractionControllerTest
Change-Id: I418af0d9d58923d5cbca1b55934271130abd0254