Revert "Merge branch 'jv-remove-duplicate-jobs-multistore' into 'master'"

This reverts commit 3dac2086, reversing
changes made to 5e5bc47a.

lib/gitlab/sidekiq_middleware/duplicate_jobs/duplicate_job.rb

@@ -220,7 +220,12 @@ def jid
         end
 
         def cookie_key
-          "#{idempotency_key}:cookie:v2"
+          # This duplicates `Gitlab::Redis::Queues::SIDEKIQ_NAMESPACE` both here and in `#idempotency_key`
+          # This is because `Sidekiq.redis` used to add this prefix automatically through `redis-namespace`
+          # and we did not notice this in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/25447
+          # Now we're keeping this as-is to avoid a key-migration when redis-namespace gets
+          # removed from Sidekiq: https://gitlab.com/groups/gitlab-com/gl-infra/-/epics/944
+          "#{Gitlab::Redis::Queues::SIDEKIQ_NAMESPACE}:#{idempotency_key}:cookie:v2"
         end
 
         def get_cookie
@@ -252,7 +257,7 @@ def reschedulable?
         end
 
         def with_redis(&block)
-          Sidekiq.redis(&block) # rubocop:disable Cop/SidekiqRedisCall
+          Gitlab::Redis::Queues.with(&block) # rubocop:disable Cop/RedisQueueUsage, CodeReuse/ActiveRecord
         end
       end
     end

spec/lib/gitlab/sidekiq_middleware/duplicate_jobs/duplicate_job_spec.rb

@@ -79,10 +79,10 @@
 
   context 'with Redis cookies' do
     def with_redis(&block)
-      Sidekiq.redis(&block)
+      Gitlab::Redis::Queues.with(&block)
     end
 
-    let(:cookie_key) { "#{idempotency_key}:cookie:v2" }
+    let(:cookie_key) { "#{Gitlab::Redis::Queues::SIDEKIQ_NAMESPACE}:#{idempotency_key}:cookie:v2" }
     let(:cookie) { get_redis_msgpack(cookie_key) }
 
     describe '#check!' do