Remove an unused import.

apm-collector/apm-collector-agent/agent-grpc/agent-grpc-provider/src/test/java/org/apache/skywalking/apm/collector/agent/grpc/provider/handler/ApplicationRegisterServiceHandlerTestCase.java

@@ -22,7 +22,6 @@ import io.grpc.ManagedChannel;
 import io.grpc.ManagedChannelBuilder;
 import org.apache.skywalking.apm.network.proto.Application;
 import org.apache.skywalking.apm.network.proto.ApplicationMapping;
-import org.apache.skywalking.apm.network.proto.ApplicationMappings;
 import org.apache.skywalking.apm.network.proto.ApplicationRegisterServiceGrpc;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;