MINOR: Fix sensor retrieval in stand0by task's constructor (#7632)

We should not use StreamsMetricsImpl. threadLevelSensor directly which would only retrieve the sensor but would not add any metrics to the sensor. Generally speaking we should always use the corresponding-level Metrics class (e.g. ThreadMetrics) to get the sensors which are populated with metrics.

Reviewers: Guozhang Wang <wangguoz@gmail.com>, John Roesler <john@confluent.io>, Bill Bejeck <bbejeck@gmail.com>, Matthias J. Sax <matthias@confluent.io>

streams/src/main/java/org/apache/kafka/streams/processor/internals/StandbyTask.java

@@ -28,6 +28,7 @@ import org.apache.kafka.streams.StreamsMetrics;
 import org.apache.kafka.streams.errors.ProcessorStateException;
 import org.apache.kafka.streams.processor.TaskId;
 import org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl;
+import org.apache.kafka.streams.processor.internals.metrics.ThreadMetrics;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -68,8 +69,7 @@ public class StandbyTask extends AbstractTask {
                 final StateDirectory stateDirectory) {
         super(id, partitions, topology, consumer, changelogReader, true, stateDirectory, config);
 
-        closeTaskSensor = metrics
-            .threadLevelSensor(Thread.currentThread().getName(), "task-closed", Sensor.RecordingLevel.INFO);
+        closeTaskSensor = ThreadMetrics.closeTaskSensor(Thread.currentThread().getName(), metrics);
         processorContext = new StandbyContextImpl(id, config, stateMgr, metrics);
 
         final Set<String> changelogTopicNames = new HashSet<>(topology.storeToChangelogTopic().values());