Datadog model-sanitization now runs on any defined model value, not just strings

In the internal Datadog telemetry pipeline, the step that checks and cleans up the model field before sending an event used to only run if the model value was a text string. Now it runs whenever the model value is defined at all, including cases where it is something else, like a number or null. If the value can't be recognized as a known model, the entire telemetry event is now dropped rather than being sent with an unrecognized or malformed model field.