[HOTFIX][SPARK-15613][SQL]Set test runtime timezone for DateTimeUtilSuite

[adrian-wang]

What changes were proposed in this pull request?

With not default timezone setting in DateTimeUtilsSuite and use Timestamp.valueOf method could cause problems in a different time zone from PST. This PR fix this reported in #13652 by @robbinspg and @lw-lin

How was this patch tested?

Existed tests do that.

cc @davies

[davies]

@adrian-wang Thanks for the PR, but there is actually a bug in toUTCTime/fromUTCTime, this PR will hide that. I created #13784 to fix the actual bug.

[ckadner]

I (also) just created a PR to fix the two test cases from UTC timestamp and to UTC timestap to respect the time zones that are supposed to be used in the conversions. I had not seen @davies latest PR in time.

@davies Would it not suffice to set the (thread local) time zone in the two test cases?

[SparkQA]

Test build #60864 has finished for PR 13783 at commit f5cea66.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • class DateTimeUtilsSuite extends SparkFunSuite with BeforeAndAfterAll

[adrian-wang]

Closing, thx!