verify route transform's component_discarded_events_total

[JeanMertz]

• Verify internal event processing metrics are tested via assert_X_compliance test helpers
• Update component_discarded_events_total to match the new instrumentation spec by adding reason to the emitted logs, and intentional to emitted logs and metrics

[JeanMertz]

I realized that this issue doesn't need to be resolved, as (1) there's no way for this transform to discard events, so component_discarded_events_total is never emitted, and (2) because of that, we don't need to use assert_X_compliance, as we're already using the COMPONENT_MULTIPLE_OUTPUTS_TESTS test specification which is specifically made for components that emit multiple events.