xds: Update an error log message. (#3429)
xds: Update an error log message. (#3429)


dfawley/grpc-go,stanley-cheung/grpc-go,dfawley/grpc-go,menghanl/grpc-go,grpc/grpc-go,stanley-cheung/grpc-go,grpc/grpc-go,menghanl/grpc-go