MotionEvent: clean up flag for PointerCoords#isResampled

This flag has now been launched in a public release, so we can remove
it.

Bug: 328781936
Test: m checkinput
Flag: EXEMPT removing com.android.hardware.input.pointer_coords_is_resampled_api
Change-Id: I37da815fe95440bfeff65db8f8e48e1a48d14362