grpc-specific scripts no longer necessary

[ignasi35]

The sample applications demo-ing gRPC usage no longer need the ALPN agent. The ssl-lagom script in https://github.com/lagom/lagom-samples/blob/1.6.x/grpc-example/grpc-example-scala/ is probably unnecessary (or at least a part of it?).

See a similar change playframework/play-samples#111