Remove unused imports

Author: acogoluegnes

src/main/java/com/rabbitmq/client/impl/MicrometerMetricsCollector.java

@@ -21,7 +21,6 @@
 import io.micrometer.core.instrument.Counter;
 import io.micrometer.core.instrument.MeterRegistry;
 
-import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
 import static com.rabbitmq.client.impl.MicrometerMetricsCollector.Metrics.ACKNOWLEDGED_MESSAGES;