Revert otlp grpc client changes

Propose change in follow up PR

Author: ethandmd

exporters/otlp/src/otlp_grpc_client.cc

@@ -333,15 +333,7 @@ std::shared_ptr<grpc::Channel> OtlpGrpcClient::MakeChannel(const OtlpGrpcClientO
   }
 
   std::shared_ptr<grpc::Channel> channel;
-  std::string grpc_target;
-  if (url.scheme_ == "unix")
-  {
-    grpc_target = "unix:" + url.path_;
-  }
-  else
-  {
-    grpc_target = url.host_ + ":" + std::to_string(static_cast<int>(url.port_));
-  }
+  std::string grpc_target = url.host_ + ":" + std::to_string(static_cast<int>(url.port_));
   grpc::ChannelArguments grpc_arguments;
   grpc_arguments.SetUserAgentPrefix(options.user_agent);