Replace config feature flag to request scoped flag
Read distribution is inherently request scoped, and as such the same infrasture could be leveraged compared to other RPCs with feature flags. Being scoped on the request, set by Rails.
This change removes the config value, and adds the feature flag.
Relates to: !2162 (merged) Closes: gitlab-development-kit#925 (closed) Closes: omnibus-gitlab#5361 (closed)
Edited by GitLab Release Tools Bot