feat: Allow metric alerts to be used in on-prem

[wedamija]

This enables metric alerts for all on-prem users. There wasn't too much to do, mostly just making
sure the consumers are running, and then enabling the feature.

[wedamija]

I tested this locally and saw metric alerts fire, so this should be good to go.

Looking at the logs, initially I saw some cimpl.KafkaException: KafkaError{code=UNKNOWN_TOPIC_OR_PART,val=3,str="Subscribed topic not available: events-subscription-results: Broker: Unknown topic or partition"}. This should resolve itself as events come in, but if we want to avoid it we could set KAFKA_CONSUMER_AUTO_CREATE_TOPICS = True in the config. Then once getsentry/sentry#21801 is merged we should be good.

[BYK]

This should resolve itself as events come in, but if we want to avoid it we could set KAFKA_CONSUMER_AUTO_CREATE_TOPICS = True in the config.

Can we set this in https://github.com/getsentry/sentry/blob/master/docker/sentry.conf.py or in our default server.py config?

[BYK]

LGTM except for the comment I left. Also I'm assuming you tested this?

[wedamija]

This should resolve itself as events come in, but if we want to avoid it we could set KAFKA_CONSUMER_AUTO_CREATE_TOPICS = True in the config.

Can we set this in https://github.com/getsentry/sentry/blob/master/docker/sentry.conf.py or in our default server.py config?

Actually it is already set to True, I realised I just saw the error due to getsentry/sentry#21801 not being merged.

LGTM except for the comment I left. Also I'm assuming you tested this?

Yep, mentioned in a comment above.

[BYK]

/cc @markstory @chadwhitacre