overlay: core: Remove accent color overrides

On Android 12, AOSP's default Theme.DeviceDefault colors are mapped to
various shades and tonal variations from the system-wide Material You
color palette. Overriding the default accent colors with these legacy
LineageOS teal colors prevents dynamic theming (Monet) from working
properly across the system as it only affects the Material You color
palette. It also creates an accessibility issue as the new design
expects specific lightness shades for the light and dark accent colors.

Remove the color overrides to fix Monet and UI colors in general.

Change-Id: I81f18d136d8d4e22c3219bea05536219bb5ce672