[SS][MINOR] Fix flaky test in DatastreamReaderWriterSuite. temp checkpoint dir should be deleted

## What changes were proposed in this pull request?

Stopping query while it is being initialized can throw interrupt exception, in which case temporary checkpoint directories will not be deleted, and the test will fail.

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

Closes #18442 from tdas/DatastreamReaderWriterSuite-fix.

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

@@ -641,6 +641,7 @@ class DataStreamReaderWriterSuite extends StreamTest with BeforeAndAfter {
   test("temp checkpoint dir should be deleted if a query is stopped without errors") {
     import testImplicits._
     val query = MemoryStream[Int].toDS.writeStream.format("console").start()
+    query.processAllAvailable()
     val checkpointDir = new Path(
       query.asInstanceOf[StreamingQueryWrapper].streamingQuery.resolvedCheckpointRoot)
     val fs = checkpointDir.getFileSystem(spark.sessionState.newHadoopConf())