Call updateColors() explicitly when theme changes

Currently, onColorPaletteChanged() in onThemeChanged() will call updateColor() from
DefaultClockController.kt. We also want it to explicitly call
updateColors() from ClockEventController.kt because it has
theme-specific settings based on region sampling. This CL is derived
from Change-Id: Id94d48c179732f2a13d96de1ad2589bb60051c43.

Bug: 202758428
Test: manual
Change-Id: I4db6e2ebca3eeed2dc76734c25fe2ecc144a0490