time-util: correctly handle the timezone when parsing

time-util: correctly handle the timezone when parsing

The timezone was cut off the string once the timezone was not UTC.
If it is not UTC but a other timezone that matches tzname[0] or
tzname[1], then we can leave it to the impl function to parse that
correctly. If not we can just fallback to whatever is the current
timezone is in the given t_timezone.

This should fix the testuite and tests.