[SPARK-21914][FOLLOWUP][TEST-HADOOP3.2][TEST-JAVA11] Clone SparkSessi…

…on per each function example

### What changes were proposed in this pull request?
In the PR, I propose to clone Spark session per-each expression example. Examples can modify SQL settings, and can influence on each other if they run in the same Spark session in parallel.

### Why are the changes needed?
This should fix test failures like [this](https://amplab.cs.berkeley.edu/jenkins/job/spark-master-test-maven-hadoop-3.2-jdk-11/478/testReport/junit/org.apache.spark.sql/SQLQuerySuite/check_outputs_of_expression_examples/) checking of the `Like` example:
```
org.apache.spark.sql.AnalysisException: the pattern '\%SystemDrive\%\Users%' is invalid, the escape character is not allowed to precede 'U';
      at org.apache.spark.sql.catalyst.util.StringUtils$.fail$1(StringUtils.scala:48)
      at org.apache.spark.sql.catalyst.util.StringUtils$.escapeLikeRegex(StringUtils.scala:57)
      at org.apache.spark.sql.catalyst.expressions.Like.escape(regexpExpressions.scala:108)
```

### Does this PR introduce any user-facing change?
No

### How was this patch tested?
By running `check outputs of expression examples` in `org.apache.spark.sql.SQLQuerySuite`

Closes #25956 from MaxGekk/fix-expr-examples-checks.

Authored-by: Maxim Gekk <max.gekk@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>

sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala

@@ -169,15 +169,17 @@ class SQLQuerySuite extends QueryTest with SharedSparkSession {
 
     withSQLConf(SQLConf.UTC_TIMESTAMP_FUNC_ENABLED.key -> "true") {
       spark.sessionState.functionRegistry.listFunction().par.foreach { funcId =>
-        val info = spark.sessionState.catalog.lookupFunctionInfo(funcId)
+        // Examples can change settings. We clone the session to prevent tests clashing.
+        val clonedSpark = spark.cloneSession()
+        val info = clonedSpark.sessionState.catalog.lookupFunctionInfo(funcId)
         val className = info.getClassName
         if (!ignoreSet.contains(className)) {
           withClue(s"Function '${info.getName}', Expression class '$className'") {
             val example = info.getExamples
             checkExampleSyntax(example)
             example.split("  > ").toList.foreach(_ match {
               case exampleRe(sql, output) =>
-                val df = spark.sql(sql)
+                val df = clonedSpark.sql(sql)
                 val actual = unindentAndTrim(
                   hiveResultString(df.queryExecution.executedPlan).mkString("\n"))
                 val expected = unindentAndTrim(output)