Capture layer and children when calling takeSurfaceControlScreenshot

When calling UiAutomationConnection.takeSurfaceControlScreenshot, it
should capture the requested SurfaceControl and its children. The
current code only captures the children. Therefore, call setChildrenOnly
with false to ensure it captures the parent, as well.

Test: ASurfaceControlTest
Bug: 185390632
Change-Id: I62707f808934177c8db05485ac28559982b8c607