[SPARK-25606][TEST] Reduce DateExpressionsSuite test time costs in Jenkins

[wangyum]

What changes were proposed in this pull request?

Reduce DateExpressionsSuite.Hour test time costs in Jenkins by reduce iteration times.

How was this patch tested?

Manual tests on my local machine.
before:

- Hour (34 seconds, 54 milliseconds)

after:

- Hour (2 seconds, 697 milliseconds)

[SparkQA]

Test build #96946 has finished for PR 22632 at commit 3256100.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[wangyum]

cc @gatorsmile @dongjoon-hyun

[gatorsmile]

LGTM

Merged to master.

[wangyum]

@gatorsmile I have some confusion. Is this

spark/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/DateExpressionsSuite.scala

Lines 118 to 122 in 58c55cb

	(0 to 5 * 24).foreach { i =>
	c.add(Calendar.HOUR_OF_DAY, 1)
	checkEvaluation(Quarter(Literal(new Date(c.getTimeInMillis))),
	c.get(Calendar.MONTH) / 3 + 1)
	}

should be

(0 to 24).foreach { h =>
  c.add(Calendar.HOUR_OF_DAY, h)
  checkEvaluation(Quarter(Literal(new Date(c.getTimeInMillis))),
    c.get(Calendar.MONTH) / 3 + 1)
}