[TEST] Ignore flaky test in StreamingQueryListenerSuite

## What changes were proposed in this pull request?

Ignoring the flaky test introduced in #15307

https://amplab.cs.berkeley.edu/jenkins/job/spark-master-test-sbt-hadoop-2.7/1736/testReport/junit/org.apache.spark.sql.streaming/StreamingQueryListenerSuite/single_listener__check_trigger_statuses/

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #15491 from tdas/metrics-flaky-test.

sql/core/src/test/scala/org/apache/spark/sql/streaming/StreamingQueryListenerSuite.scala

@@ -43,7 +43,7 @@ class StreamingQueryListenerSuite extends StreamTest with BeforeAndAfter {
     // Make sure we don't leak any events to the next test
   }
 
-  test("single listener, check trigger statuses") {
+  ignore("single listener, check trigger statuses") {
     import StreamingQueryListenerSuite._
     clock = new ManualClock()