[SPARK-3329][SQL] Don't depend on Hive SET pair ordering in tests.

This fixes some possible spurious test failures in `HiveQuerySuite` by comparing sets of key-value pairs as sets, rather than as lists.

Author: William Benton <willb@redhat.com>
Author: Aaron Davidson <aaron@databricks.com>

Closes #2220 from willb/spark-3329 and squashes the following commits:

3b3e205 [William Benton] Collapse collectResults case match in HiveQuerySuite
6525d8e [William Benton] Handle cases where SET returns Rows of (single) strings
cf11b0e [Aaron Davidson] Fix flakey HiveQuerySuite test

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala

@@ -558,62 +558,67 @@ class HiveQuerySuite extends HiveComparisonTest {
     val testKey = "spark.sql.key.usedfortestonly"
     val testVal = "test.val.0"
     val nonexistentKey = "nonexistent"
-
+    val KV = "([^=]+)=([^=]*)".r
+    def collectResults(rdd: SchemaRDD): Set[(String, String)] = 
+      rdd.collect().map { 
+        case Row(key: String, value: String) => key -> value 
+        case Row(KV(key, value)) => key -> value
+      }.toSet
     clear()
 
     // "set" itself returns all config variables currently specified in SQLConf.
     // TODO: Should we be listing the default here always? probably...
     assert(sql("SET").collect().size == 0)
 
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql(s"SET $testKey=$testVal").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(hql(s"SET $testKey=$testVal"))
     }
 
     assert(hiveconf.get(testKey, "") == testVal)
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql(s"SET $testKey=$testVal").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(hql("SET"))
     }
 
     sql(s"SET ${testKey + testKey}=${testVal + testVal}")
     assert(hiveconf.get(testKey + testKey, "") == testVal + testVal)
-    assertResult(Array(s"$testKey=$testVal", s"${testKey + testKey}=${testVal + testVal}")) {
-      sql(s"SET").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal, (testKey + testKey) -> (testVal + testVal))) {
+      collectResults(hql("SET"))
     }
 
     // "set key"
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql(s"SET $testKey").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(hql(s"SET $testKey"))
     }
 
-    assertResult(Array(s"$nonexistentKey=<undefined>")) {
-      sql(s"SET $nonexistentKey").collect().map(_.getString(0))
+    assertResult(Set(nonexistentKey -> "<undefined>")) {
+      collectResults(hql(s"SET $nonexistentKey"))
     }
 
     // Assert that sql() should have the same effects as sql() by repeating the above using sql().
     clear()
     assert(sql("SET").collect().size == 0)
 
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql(s"SET $testKey=$testVal").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(sql(s"SET $testKey=$testVal"))
     }
 
     assert(hiveconf.get(testKey, "") == testVal)
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql("SET").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(sql("SET"))
     }
 
     sql(s"SET ${testKey + testKey}=${testVal + testVal}")
     assert(hiveconf.get(testKey + testKey, "") == testVal + testVal)
-    assertResult(Array(s"$testKey=$testVal", s"${testKey + testKey}=${testVal + testVal}")) {
-      sql("SET").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal, (testKey + testKey) -> (testVal + testVal))) {
+      collectResults(sql("SET"))
     }
 
-    assertResult(Array(s"$testKey=$testVal")) {
-      sql(s"SET $testKey").collect().map(_.getString(0))
+    assertResult(Set(testKey -> testVal)) {
+      collectResults(sql(s"SET $testKey"))
     }
 
-    assertResult(Array(s"$nonexistentKey=<undefined>")) {
-      sql(s"SET $nonexistentKey").collect().map(_.getString(0))
+    assertResult(Set(nonexistentKey -> "<undefined>")) {
+      collectResults(sql(s"SET $nonexistentKey"))
     }
 
     clear()