Pointer Icon Refactor: Remove get/setVirtualMousePointerDisplayId

The API is no longer needed when the refactoring is enabled, since the
creation of the associated mouse will automatically create a mouse
pointer for the display.

Bug: 311651709
Test: atest InputControllerTest
Test: atest VirtualDeviceManagerServiceTest
Change-Id: Ic5fedd6fb5951f213ea8158e33db05025e2adb7e