Reset DateFormat.is24Hour after each test

Bug: 20899571
Bug: 20937589
Bug: 20939139
Bug: 20378566
Bug: 21585934
Bug: https://code.google.com/p/android/issues/detail?id=162384
(cherry-picked from commit f3a73a96c7500726862d6a25b4fba9193c2df630)

Change-Id: I4cc2b72bff99eb0b64ec5f078eae1ec240c4d5cd
1 file changed