Merge branch 'ps-add-sourcegraph-feature-flag-yml' into 'master'

Add Sourcegraph feature flag yml and ref to `Feature.enabled?` [RUN ALL RSPEC]

See merge request gitlab-org/gitlab!50234

config/feature_flags/development/sourcegraph.yml

+---
+name: sourcegraph
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/16556
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/292199
+milestone: '12.5'
+type: development
+group: group::editor
+default_enabled: false

lib/gitlab/sourcegraph.rb

@@ -13,7 +13,8 @@ module Gitlab
       end
 
       def feature_enabled?(actor = nil)
-        feature.enabled?(actor)
+        # Some CI jobs grep for Feature.enabled? in our codebase, so it is important this reference stays around.
+        Feature.enabled?(:sourcegraph, actor)
       end
 
       private