Adds the old timezone to dumpsys logs after a timezone update.

This makes it easier to understand timezone change logs. This will also make it easier to automatically parse the timezone change logs, as all the relevant information about a timezone change is now included in the timezone change log line.

Change-Id: I18664e3465c0c6145a87010e9928e10167b15567
Flag: EXEMPT log only update
Bug: 290318043