Verify pulsar sink

[prognant]

• 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
• Verify that the component correctly emits the correct error events per the component spec

[prognant]

Encoding failure are the only non-recoverable, thus component_discarded_events_total matches the new instrumentation spec thanks to #14021.

[jszwedko]

@prognant I think the pulsar sink is not emitting an error whenever the send fails?

vector/src/sinks/pulsar.rs

Lines 359 to 363 in 553763f

	Some((Err(error), _, finalizers)) => {
	finalizers.update_status(EventStatus::Errored);
	error!(message = "Pulsar sink generated an error.", %error);
	return Poll::Ready(Err(()));
	}

I'll reopen, but let me know if I'm wrong.