POST EventsReceiver/Post returns 500 if eformidling message has expired

### Description of the bug

When POST EventsReceiver/Post returns 500 when the eformidling message being checked has expired.
```The message lifetime has expired. Error from Eformidling```

The endpoint should handle this status update some metric and log an error and return 200 status to the eventsystem.
The metrics and logs are to make it possible to create alerts for these situations and returning 200 is to stop the eventsystem retrying the delivery, as there is nothing more we can do at this point.

### Steps To Reproduce

Create a message in eFormidling let it expire and see the error from the eventssystem

### Additional Information

_No response_

Start at the POST EventsReceiver/Post endpoint and trace how an expired eFormidling message is handled. Reproduce the case by creating a message in eFormidling and letting it expire. Done means the endpoint records a metric, logs the error, and returns HTTP 200 so the event system does not retry.

Written by the indexing model from the issue text.