[lldb] Revert some change in data-formatter-objc/main.m that broke TestDataFormatterObjCNSDate.py

Changing the date2 to an timezone independent value broke the test as the data formatters
uses the current time zone for the summary (so changing it to a time zone independent value
would again break the test in some time zones). We anyway just care about this for date2
which will be printed in a timezone-independent summary.