Remove libcore.icu.LocaleData.shortDateFormat4.

shortDateFormat4 was used to support "Choose date format" which was
removed in commit f91f06a5991451e4af3cf99eba791cb3009810d2 (bug
18322220).

It is now completely unused.

Bug: 18407262
Change-Id: I753ff0d1aaed0a8e2c0815974e0e0326b878ff69
1 file changed