[SPARK-27145][MINOR] Close store in the SQLAppStatusListenerSuite after test

## What changes were proposed in this pull request?
We create many stores in the SQLAppStatusListenerSuite, but we need to the close store after test.

## How was this patch tested?
Existing tests

Closes #24079 from shahidki31/SPARK-27145.

Authored-by: Shahid <shahidki31@gmail.com>
Signed-off-by: Marcelo Vanzin <vanzin@cloudera.com>

Author: shahidki31

sql/core/src/test/scala/org/apache/spark/sql/execution/ui/AllExecutionsPageSuite.scala

@@ -24,6 +24,7 @@ import javax.servlet.http.HttpServletRequest
 import scala.xml.Node
 
 import org.mockito.Mockito.{mock, when, RETURNS_SMART_NULLS}
+import org.scalatest.BeforeAndAfter
 
 import org.apache.spark.scheduler.{JobFailed, SparkListenerJobEnd, SparkListenerJobStart}
 import org.apache.spark.sql.DataFrame
@@ -32,10 +33,19 @@ import org.apache.spark.sql.test.SharedSQLContext
 import org.apache.spark.status.ElementTrackingStore
 import org.apache.spark.util.kvstore.InMemoryStore
 
-class AllExecutionsPageSuite extends SharedSQLContext {
+class AllExecutionsPageSuite extends SharedSQLContext with BeforeAndAfter {
 
   import testImplicits._
 
+  var kvstore: ElementTrackingStore = _
+
+  after {
+    if (kvstore != null) {
+      kvstore.close()
+      kvstore = null
+    }
+  }
+
   test("SPARK-27019: correctly display SQL page when event reordering happens") {
     val statusStore = createStatusStore
     val tab = mock(classOf[SQLTab], RETURNS_SMART_NULLS)
@@ -70,9 +80,9 @@ class AllExecutionsPageSuite extends SharedSQLContext {
 
   private def createStatusStore: SQLAppStatusStore = {
     val conf = sparkContext.conf
-    val store = new ElementTrackingStore(new InMemoryStore, conf)
-    val listener = new SQLAppStatusListener(conf, store, live = true)
-    new SQLAppStatusStore(store, Some(listener))
+    kvstore = new ElementTrackingStore(new InMemoryStore, conf)
+    val listener = new SQLAppStatusListener(conf, kvstore, live = true)
+    new SQLAppStatusStore(kvstore, Some(listener))
   }
 
   private def createTestDataFrame: DataFrame = {

sql/core/src/test/scala/org/apache/spark/sql/execution/ui/SQLAppStatusListenerSuite.scala

@@ -22,6 +22,7 @@ import java.util.Properties
 import scala.collection.mutable.ListBuffer
 
 import org.json4s.jackson.JsonMethods._
+import org.scalatest.BeforeAndAfter
 
 import org.apache.spark._
 import org.apache.spark.LocalSparkContext._
@@ -43,13 +44,24 @@ import org.apache.spark.util.{AccumulatorMetadata, JsonProtocol, LongAccumulator
 import org.apache.spark.util.kvstore.InMemoryStore
 
 
-class SQLAppStatusListenerSuite extends SparkFunSuite with SharedSQLContext with JsonTestUtils {
+class SQLAppStatusListenerSuite extends SparkFunSuite with SharedSQLContext with JsonTestUtils
+  with BeforeAndAfter {
+
   import testImplicits._
 
   override protected def sparkConf = {
     super.sparkConf.set(LIVE_ENTITY_UPDATE_PERIOD, 0L).set(ASYNC_TRACKING_ENABLED, false)
   }
 
+  private var kvstore: ElementTrackingStore = _
+
+  after {
+    if (kvstore != null) {
+      kvstore.close()
+      kvstore = null
+    }
+  }
+
   private def createTestDataFrame: DataFrame = {
     Seq(
       (1, 1),
@@ -126,9 +138,9 @@ class SQLAppStatusListenerSuite extends SparkFunSuite with SharedSQLContext with
 
   private def createStatusStore(): SQLAppStatusStore = {
     val conf = sparkContext.conf
-    val store = new ElementTrackingStore(new InMemoryStore, conf)
-    val listener = new SQLAppStatusListener(conf, store, live = true)
-    new SQLAppStatusStore(store, Some(listener))
+    kvstore = new ElementTrackingStore(new InMemoryStore, conf)
+    val listener = new SQLAppStatusListener(conf, kvstore, live = true)
+    new SQLAppStatusStore(kvstore, Some(listener))
   }
 
   test("basic") {
@@ -548,9 +560,9 @@ class SQLAppStatusListenerSuite extends SparkFunSuite with SharedSQLContext with
 
   test("eviction should respect execution completion time") {
     val conf = sparkContext.conf.clone().set(UI_RETAINED_EXECUTIONS.key, "2")
-    val store = new ElementTrackingStore(new InMemoryStore, conf)
-    val listener = new SQLAppStatusListener(conf, store, live = true)
-    val statusStore = new SQLAppStatusStore(store, Some(listener))
+    kvstore = new ElementTrackingStore(new InMemoryStore, conf)
+    val listener = new SQLAppStatusListener(conf, kvstore, live = true)
+    val statusStore = new SQLAppStatusStore(kvstore, Some(listener))
 
     var time = 0
     val df = createTestDataFrame