a11y: Fix autoclick indicator positioning when magnified

When magnification is enabled there becomes two sets of onscreen
coordinates, magnified and non-magnified. This changes guarantees the
indicator remains in the non-magnified space so it'll awlays match the
cursor's actual location.

Screenshot: http://b/393191656#comment2

Bug: b/393191656
Test: AutoclickControllerTest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: Id5d2f1631f5b38b684d5769e901d80acc425a0c7