fix build

Author: panchenko

util/src/test/java/io/grpc/util/GracefulSwitchLoadBalancerTest.java

@@ -21,7 +21,6 @@
 import static io.grpc.ConnectivityState.IDLE;
 import static io.grpc.ConnectivityState.READY;
 import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;
-import static io.grpc.util.GracefulSwitchLoadBalancer.BUFFER_PICKER;
 import static org.junit.Assert.assertThrows;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;