Performance test ActionCable with Puma
This is related to the discussion we had in gitlab-org/memory-team/team-tasks#39 (comment 334231800)
This feature is still experimental but eventually we'd need a way to run performance tests for these real-time features.
During the working group meeting, it was also mentioned that a first step here could be to just run the existing performance tests with the feature enabled to make sure that we are not introducing a performance regression.
This would need some configuration to enable the ActionCable Puma server and also the feature flags.