[Alerting] should pre-configured actions never return their config?

[pmuellr]

When support for pre-configured alerts landed, the UI was changed to not display their config, as this was specified in the original design to work that way. There's some question as to whether that's what we really want to do, but if it is what we want to do, then we likely need to lock down the http endpoint and action client, to not return the config settings in their "GET" APIs. Currently, they both return the config data.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[mikecote]

It has been discussed at the sync that we shouldn't return the config for now and that we'll wait for user feedback before creating an issue to display the config values.

This issue is now scoped to not return the config from the action APIs (get and getAll).