[SPARK-16050][TESTS] Remove the flaky test: ConsoleSinkSuite

## What changes were proposed in this pull request?

ConsoleSinkSuite just collects content from stdout and compare them with the expected string. However, because Spark may not stop some background threads at once, there is a race condition that other threads are outputting logs to **stdout** while ConsoleSinkSuite is running. Then it will make ConsoleSinkSuite fail.

Therefore, I just deleted `ConsoleSinkSuite`. If we want to test ConsoleSinkSuite in future, we should refactoring ConsoleSink to make it testable instead of depending on stdout. Therefore, this test is useless and I just delete it.

## How was this patch tested?

Just removed a flaky test.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #13776 from zsxwing/SPARK-16050.

sql/core/src/test/scala/org/apache/spark/sql/execution/streaming/ConsoleSinkSuite.scala

-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.spark.sql.execution.streaming
-
-import java.io.{ByteArrayOutputStream, PrintStream}
-import java.nio.charset.StandardCharsets.UTF_8
-
-import org.scalatest.BeforeAndAfter
-
-import org.apache.spark.sql.streaming.StreamTest
-
-class ConsoleSinkSuite extends StreamTest with BeforeAndAfter {
-
-  import testImplicits._
-
-  after {
-    sqlContext.streams.active.foreach(_.stop())
-  }
-
-  test("SPARK-16020 Complete mode aggregation with console sink") {
-    withTempDir { checkpointLocation =>
-      val origOut = System.out
-      val stdout = new ByteArrayOutputStream()
-      try {
-        // Hook Java System.out.println
-        System.setOut(new PrintStream(stdout))
-        // Hook Scala println
-        Console.withOut(stdout) {
-          val input = MemoryStream[String]
-          val df = input.toDF().groupBy("value").count()
-          val query = df.writeStream
-            .format("console")
-            .outputMode("complete")
-            .option("checkpointLocation", checkpointLocation.getAbsolutePath)
-            .start()
-          input.addData("a")
-          query.processAllAvailable()
-          input.addData("a", "b")
-          query.processAllAvailable()
-          input.addData("a", "b", "c")
-          query.processAllAvailable()
-          query.stop()
-        }
-        System.out.flush()
-      } finally {
-        System.setOut(origOut)
-      }
-
-      val expected = """-------------------------------------------
-        |Batch: 0
-        |-------------------------------------------
-        |+-----+-----+
-        ||value|count|
-        |+-----+-----+
-        ||    a|    1|
-        |+-----+-----+
-        |
-        |-------------------------------------------
-        |Batch: 1
-        |-------------------------------------------
-        |+-----+-----+
-        ||value|count|
-        |+-----+-----+
-        ||    a|    2|
-        ||    b|    1|
-        |+-----+-----+
-        |
-        |-------------------------------------------
-        |Batch: 2
-        |-------------------------------------------
-        |+-----+-----+
-        ||value|count|
-        |+-----+-----+
-        ||    a|    3|
-        ||    b|    2|
-        ||    c|    1|
-        |+-----+-----+
-        |
-        |""".stripMargin
-      assert(expected === new String(stdout.toByteArray, UTF_8))
-    }
-  }
-
-}