feat: enable grpc.lb.locality label for client-side metrics (#2659)

Author: frankyn

google-cloud-storage/src/main/java/com/google/cloud/storage/OpenTelemetryBootstrappingUtils.java

@@ -102,6 +102,7 @@ static void enableGrpcMetrics(
     GrpcOpenTelemetry grpcOpenTelemetry =
         GrpcOpenTelemetry.newBuilder()
             .sdk(openTelemetrySdk)
+            .addOptionalLabel("grpc.lb.locality")
             .enableMetrics(METRICS_TO_ENABLE)
             .build();
     ApiFunction<ManagedChannelBuilder, ManagedChannelBuilder> channelConfigurator =