[SPARK-28714][SQL][TEST] Add hive.aux.jars.path test for spark-sql shell

[wangyum]

What changes were proposed in this pull request?

Utilities.addToClassPath has been changed since HIVE-22096, but we use it to add plugin jars:

spark/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala

Lines 144 to 147 in 128ea37

	val auxJars = HiveConf.getVar(conf, HiveConf.ConfVars.HIVEAUXJARS)
	if (StringUtils.isNotBlank(auxJars)) {
	loader = Utilities.addToClassPath(loader, StringUtils.split(auxJars, ","))
	}

This PR add test for spark-sql adding plugin jars.

How was this patch tested?

N/A

[SparkQA]

Test build #109044 has finished for PR 25435 at commit 838da98.

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

[dongjoon-hyun]

+1, LGTM. Merged to master.
Thank you, @wangyum .