Ensure that installation from source uses sidekiq-cluster
With #170 (closed) in place, we're able to use sidekiq-cluster
(through an ENV var) at https://gitlab.com/gitlab-org/gitlab/blob/master/lib/support/init.d/gitlab#L461. Ideally we should validate at least GDK works well in that setup before moving to Source installations.
From gitlab-org/gitlab#34396 (closed)Old description.
We also allow users to install and run [GitLab from source](https://gitlab.com/gitlab-org/gitlab-foss/blob/master/doc/install/installation.md). This comes with a significant amount of configuration and setup overhead for users, but it is an option we provide. These users would be affected by this change, because they use the bin/background_jobs script as part of an init.d supervision script we provide, and which under the current proposal would now launch sidekiq-cluster instead. This may or may not be a drop-in replacement, depending on how much the background_jobs script will have to change and/or if additional variables need to be set e.g. through the environment.