[SPARK-45300][SQL][TESTS] Remove JDK 8 workaround in TimestampFormatterSuite

[HyukjinKwon]

What changes were proposed in this pull request?

This PR removes the legacy workaround for JDK 8 in #28736.

Why are the changes needed?

• We still need the main code for completeness, and in case there are other diff in the future JDK versions so this PR only fixes the tests.
• We dropped JDK 11/8 at SPARK-44112

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Fixed unittests.

Was this patch authored or co-authored using generative AI tooling?

No.

[HyukjinKwon]

cc @yaooqinn

[yaooqinn]

LGTM

[HyukjinKwon]

cc @wangyum from 412d86e

[LuciferYang]

LGTM

[dongjoon-hyun]

Could you fix the compilation issue (due to the unused import), @HyukjinKwon ?

[error] /Users/dongjoon/APACHE/spark-merge/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/TimestampFormatterSuite.scala:22:34: Unused import
[error] import org.apache.commons.lang3.{JavaVersion, SystemUtils}
[error]                                  ^
[error] /Users/dongjoon/APACHE/spark-merge/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/TimestampFormatterSuite.scala:22:47: Unused import
[error] import org.apache.commons.lang3.{JavaVersion, SystemUtils}
[error]                                               ^

[dongjoon-hyun]

+1, LGTM.

[dongjoon-hyun]

I manually verified this. Merged to master.

$ build/sbt "catalyst/testOnly *.TimestampFormatterSuite"
...
[info] TimestampFormatterSuite:
[info] - explicitly forbidden datetime patterns (355 milliseconds)
[info] - SPARK-31939: Fix Parsing day of year when year field pattern is missing (50 milliseconds)
[info] - parsing timestamps using time zones (2 milliseconds)
[info] - format timestamps using time zones (6 milliseconds)
[info] - roundtrip micros -> timestamp -> micros using timezones (22 milliseconds)
[info] - roundtrip timestamp -> micros -> timestamp using timezones (8 milliseconds)
[info] - case insensitive parsing of am and pm (5 milliseconds)
[info] - format fraction of second (1 millisecond)
[info] - formatting negative years with default pattern (3 milliseconds)
[info] - parsing timestamp strings with various seconds fractions (8 milliseconds)
[info] - formatting timestamp strings up to microsecond precision (4 milliseconds)
[info] - SPARK-30958: parse timestamp with negative year (2 milliseconds)
[info] - SPARK-31557: rebasing in legacy formatters/parsers (10 milliseconds)
[info] - parsing hour with various patterns (3 milliseconds)
[info] - missing date fields (0 milliseconds)
[info] - missing year field with invalid date (1 millisecond)
[info] - missing am/pm field (1 millisecond)
[info] - missing time fields (1 millisecond)
[info] - missing hour field (0 milliseconds)
[info] - check result differences for datetime formatting (0 milliseconds)
[info] - SPARK-32424: avoid silent data change when timestamp overflows (1 millisecond)
[info] - SPARK-36418: default parsing w/o pattern (5 milliseconds)
[info] - SPARK-39193: support returning optional parse results in the default formatter (2 milliseconds)
[info] - SPARK-39280: support returning optional parse results in the iso8601 formatter (0 milliseconds)
[info] - SPARK-39281: support returning optional parse results in the legacy formatter (0 milliseconds)
[info] Run completed in 1 second, 193 milliseconds.
[info] Total number of tests run: 25
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 25, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
[success] Total time: 27 s, completed Sep 25, 2023, 8:14:13 PM