[FE] SimpleDateFormat needs to set timezone

[vagetablechicken]

Describe the bug

In UT DynamicPartitionUtilTest, we set calendar timezone by TimeUtils.getDefaultTimeZone().
https://github.com/apache/incubator-doris/blob/2ce2cf78acc298a094771d1b6df602aeddb3e8d1/fe/src/test/java/org/apache/doris/common/util/DynamicPartitionUtilTest.java#L56-L62
But we parse calendar.getTime(). It's a Date, Date has no time zone. So the Date obj is back to GMT/UTC.
https://github.com/apache/incubator-doris/blob/2ce2cf78acc298a094771d1b6df602aeddb3e8d1/fe/src/main/java/org/apache/doris/common/util/DynamicPartitionUtil.java#L429-L435

So does Calendar::setTime().
https://github.com/apache/incubator-doris/blob/30b712c1584281e4831ea900154e4240e78861ff/fe/src/main/java/org/apache/doris/common/util/DynamicPartitionUtil.java#L336

To solve it, SimpleDateFormat could set the same timezone with calendar. We shouldn't relay on the current timezone of system.

To Reproduce
Steps to reproduce the behavior:

1. set system timezone to other
2. run fe ut DynamicPartitionUtilTest

Additional context
This issue only focuses on Calendar & SimpleDateFormat. We think calendar has its timezone, but getTime() will give the GMT/UTC time. We will use SimpleDateFormat's timezone to format it(Date obj).
Maybe there are other problems about timezone. Need more attention.