message: grpc/json transcoder: fix bad assert
  there is a buggy ASSERT in the grpc-json transcoder filter
  if the proto config for the filter uses an inlined proto_descriptor_bin instead of a file reference proto_descriptor, this assert will fail
diff: @@ -16,9 +16,6 @@ namespace GrpcJsonTranscoder {
  Server::Configuration::HttpFilterFactoryCb GrpcJsonTranscoderFilterConfig::createFilter(
  const envoy::config::filter::http::transcoder::v2::GrpcJsonTranscoder& proto_config,
  const std::string&, Server::Configuration::FactoryContext&) {
  - ASSERT(!proto_config.proto_descriptor().empty());
  - ASSERT(proto_config.services_size() > 0);
  -
  JsonTranscoderConfigSharedPtr filter_config =
  std::make_shared<JsonTranscoderConfig>(proto_config);
  