Fix WallpaperPicker styles to work properly

When not using CustomizationTheme (ie, when TP is not
available) we use WallpaperTheme instead of
CustomizationTheme, and this one was left behind in the last
refactoring.

Bug: 133480934
Change-Id: I18de72690ecd602164bd8813f7c8acfcf615e7fc
9 files changed