Include the actual error message on gRPC failure

[mdii]

Feature Request

Motivation

Currently when there is a gRPC error a tracing event is generated at the error level with the generic response failed message. We can see this event in the logs as well. However, the message is not informative and it hides the actual error.

Proposal

We need to modify DefaultOnFailure and GrpcErrorsAsFailures so that the error message and the status code are available in the on_failure() method.

[davidpdrsn]

Please write a more helpful issue title.