Show CJK dates as all-numeric in the DatePicker.

Before, we'd have something like 2006 4月12. After, we have 2006 4 12.
The alternative would require using custom NumberPicker.Formatter instances
for the year and day fields in these locales, and that seems significantly
more disruptive.

Bug: 8766552
Change-Id: I568578aae2f80f2acfc53cd277ef3beae6743472