is unable to print the letter we need to mark the letter as failed.
If we mark the letter as a technical-failure, we say that we will fix
the issue, which is wrong because we can not fix the issue.
If we mark the letter as validation-failed, the letter is in wrong
bucket so the letter is not viewable/downloadable by the client.
This PR updates the message for a letter marked as permanent-failure to
better reflect what has actually happened.