Re-enable libcore.java.util.LocaleTest with fix

- This time it wont break the build
- Remove side-effects from initDefault and make
it accessible from LocaleTest.
- initDefaults reads "user.locale" first
- Fixed failing tests in LocaleTest:
* Builder#setLocale should normalize variants
* getISO3Language/Country should throw
MissingResourceException if language/country
is not empty and ICU.getISOLanguage/Country
fails to return non-empty string
* Added NPE throw for Builder#removeUnicodeLocaleAttribute
arguments
* openJdk Locale language can have 2 to 8
characters, not 2 to 3.

Bug: 26352408
Change-Id: Ice537112c3de31ad5fcb5de2c10be75fc012172d
4 files changed