fix(storage): retry kUnauthenticated error

When using the grpc client for the google cloud storage, we sometimes have issues connecting to the authentication server. Currently, those errors are not retried. This change ensures that we can retry authentication errors when sending queries to google cloud storage using the grpc client.

Author: Nicop06

google/cloud/storage/retry_policy.h

@@ -32,7 +32,8 @@ struct StatusTraits {
     return status.code() != StatusCode::kDeadlineExceeded &&
            status.code() != StatusCode::kInternal &&
            status.code() != StatusCode::kResourceExhausted &&
-           status.code() != StatusCode::kUnavailable;
+           status.code() != StatusCode::kUnavailable &&
+           status.code() != StatusCode::kUnauthenticated;
   }
 };
 }  // namespace internal