Treat sts::IdpCommunicationError as a transient error

[rcoh]

Currently, it's modeled as an unretryable client error. This needs to either be modeled upstream or as a customization

[jdisanti]

The modeled error type for this: com.amazonaws.sts#IDPCommunicationErrorException

Documentation:

The request could not be fulfilled because the identity provider (IDP) that was asked to verify the incoming identity token could not be reached. This is often a transient error caused by network conditions. Retry the request a limited number of times so that you don't exceed the request rate. If the error persists, the identity provider might be down or not responding.