Fix testCursorIsOnRight test case

This is partial revert of Ie932903845645e50cfa0cb428babb31a44babc47

The root cause is MeasuredText.getParagraphDir respect requsted text
direction even if it is an empty text. Ideally we don't need to create
MeasuredText object for empty string but for safety, reverted to the
original code.

Bug: 70384435
Test: bit FrameworksCoreTests:android.widget.EditorCursorTest
Change-Id: Id24405f476c50fa27743589a640281d96de1c9ce