403 and 404 responses should be fatal

The issue

If the endpoint requires authentication and the connector is not configured with correct authentication and credentials, the endpoint throws 403. This should be considered fatal. The connector should never continue.

Similarly, if the endpoint URL path is misconfigured, Prometheus may respond with a 404. This should also be considered fatal.

With the current behaviour, every 4xx exception (except 429) is considered "non-retriable" as by specs, and the connector discard and continue. But 403 and 404 are usually caused by a misconfiguration, and the connector should fail.

Change required

The error handling behaviour should be ignored on 403 or 404 responses. The writer should always throw an exception