Improve nine patch scaling

Apply separate coefficient for X and Y, when scaling nine patch
lattice dividers. This is reducing rounding error and fixing
a nine patch issue in Clock app alarm background.
There are other issues in nine patch scaling (see ag/3378768).

Test: Ran clock app
Bug: 70353853
Change-Id: Ibbbfddc47767fb3314cdb88820e520b3f472e727