Remove unused fields from TimeUtil

[danielfeismann]

Since we don't use these fields any longer they could be removed to reduce complexity.

• zoneId
• getTimeZone
• getLocale

[danielfeismann]

What do you think? @t-ober @sebastian-peter @jo-bao

[sebastian-peter]

I think it's fine since you can still pass DateTimeFormatters to the remaining TimeUtil constructor, that can include override zones and locals.