KeyguardClockPositionAlgorithm Test updates

Remove the concept of a 'preferred clock y'... not in use
anymore. Existing algo tests were designed around everything being
centered on the screen and isn't relevant. Update to reflect
everything being top-aligned.

Fixes: 190849712
Test: atest KeyguardClockPositionAlgorithmTest
Change-Id: I0a5fafb5ec36ffe6f98fdc6a44e46a65c821cc0c