grpcweb_proxy.go: remove deprecated methods usage

[lumtis]

starport/services/chain/grpcweb_proxy.go we are using grpc.WithCodec and grpc.CustomCodec methods which are deprecated functions.
We can't update to the new grpc.WithDefaultCallOptions(grpc.ForceCodec(_)) method because proxy.Codec() doesn't fully implement the interface.
We may need to use another proxy or create an issue on https://github.com/mwitkow/grpc-proxy

[aljo242]

@lubtd do you know the status of this issue?

[salmad3]

Seems like methods are no longer use - closing as stale, please reopen if otherwise.