Send batch outcomes to aggregator

[Dav1dde]

Instead of sending outcomes directly to the outcome_producer, they should be sent to the outcome_aggregator for another layer of aggregation.

Code:

relay/relay-server/src/endpoints/batch_outcomes.rs

Lines 14 to 17 in f92a170

	let producer = &state.outcome_producer();
	for outcome in body.inner.outcomes {
	producer.send(outcome);
	}

This means the aggregator needs to understand TrackRawOutcome or we want to potentially change the API (purely an internal API, so that's feasible).

[linear]

RELAY-189

[jjbayer]

Pro:

• Aggregation can only become better -> less load on Kafka. One could argue that outcome batches are already aggregated, but because we run very few processing Relays these days, aggregation should improve by doing it again.

Con:

• More delays in outcome delivery. This should not matter much, we already accept a similar delay for metrics.