MINOR: Mark RocksDBStoreTest as integration test (#7412)

shouldNotThrowExceptionOnRestoreWhenThereIsPreExistingRocksDbFiles takes
1m30s, which is too long for a unit test.

`RocksDBTimestampedStoreTest` inherits from `RocksDBStoreTest` and it's
implicitly considered an integration test too.

Reviewers: Guozhang Wang <guozhang@confluent.io>

streams/src/test/java/org/apache/kafka/streams/state/internals/RocksDBStoreTest.java

@@ -34,12 +34,14 @@ import org.apache.kafka.streams.state.RocksDBConfigSetter;
 import org.apache.kafka.streams.state.internals.metrics.RocksDBMetrics;
 import org.apache.kafka.streams.state.internals.metrics.RocksDBMetricsRecorder;
 import org.apache.kafka.streams.state.internals.metrics.RocksDBMetricsRecordingTrigger;
+import org.apache.kafka.test.IntegrationTest;
 import org.apache.kafka.test.InternalMockProcessorContext;
 import org.apache.kafka.test.StreamsTestUtils;
 import org.apache.kafka.test.TestUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.junit.experimental.categories.Category;
 import org.junit.runner.RunWith;
 import org.powermock.core.classloader.annotations.PrepareForTest;
 import org.powermock.modules.junit4.PowerMockRunner;
@@ -75,6 +77,7 @@ import static org.junit.Assert.fail;
 import static org.powermock.api.easymock.PowerMock.replay;
 import static org.powermock.api.easymock.PowerMock.verify;
 
+@Category(IntegrationTest.class)
 @RunWith(PowerMockRunner.class)
 @PrepareForTest({RocksDBMetrics.class, Sensor.class})
 public class RocksDBStoreTest {