Reorder Sidekiq client middleware

The new order is as follows:

- ::Gitlab::SidekiqMiddleware::WorkerContext::Client
  Context for batch jobs
- ::Labkit::Middleware::Sidekiq::Client
  Serialize the context into the job hash
- ::Gitlab::SidekiqMiddleware::DuplicateJobs::Client
  Drop the job if needed
- ::Gitlab::SidekiqStatus::ClientMiddleware
  Keep track of the status of the job
- ::Gitlab::SidekiqMiddleware::AdminMode::Client
  Run the job with elevated permissions or not
- ::Gitlab::SidekiqMiddleware::ClientMetrics
  Count the enqueued job

This makes sure we add the logging information in the beginning of the
chain, as it could be needed for log messages coming form the other
middlewares.

Next we're doing deduplication, so we can skip any other work that
might not be needed.

The last step are the metrics, which counts enqueued jobs, this makes
sure that if anything happens in the chain, we don't count an enqueued
job. If that middleware is before the deduplication, count jobs that
might be dropped as enqueued.

lib/gitlab/sidekiq_middleware.rb

@@ -29,12 +29,12 @@ module Gitlab
     # eg: `config.client_middleware(&Gitlab::SidekiqMiddleware.client_configurator)`
     def self.client_configurator
       lambda do |chain|
-        chain.add ::Gitlab::SidekiqStatus::ClientMiddleware
-        chain.add ::Gitlab::SidekiqMiddleware::ClientMetrics
         chain.add ::Gitlab::SidekiqMiddleware::WorkerContext::Client # needs to be before the Labkit middleware
         chain.add ::Labkit::Middleware::Sidekiq::Client
-        chain.add ::Gitlab::SidekiqMiddleware::AdminMode::Client
         chain.add ::Gitlab::SidekiqMiddleware::DuplicateJobs::Client
+        chain.add ::Gitlab::SidekiqStatus::ClientMiddleware
+        chain.add ::Gitlab::SidekiqMiddleware::AdminMode::Client
+        chain.add ::Gitlab::SidekiqMiddleware::ClientMetrics
       end
     end
   end

spec/lib/gitlab/sidekiq_middleware_spec.rb

@@ -134,12 +134,12 @@ describe Gitlab::SidekiqMiddleware do
     let(:middleware_expected_args) { [worker_class_arg, job, queue, redis_pool] }
     let(:expected_middlewares) do
       [
-        Gitlab::SidekiqStatus::ClientMiddleware,
-        Gitlab::SidekiqMiddleware::ClientMetrics,
-        Gitlab::SidekiqMiddleware::WorkerContext::Client,
-        Labkit::Middleware::Sidekiq::Client,
-        Gitlab::SidekiqMiddleware::AdminMode::Client,
-        Gitlab::SidekiqMiddleware::DuplicateJobs::Client
+         ::Gitlab::SidekiqMiddleware::WorkerContext::Client,
+         ::Labkit::Middleware::Sidekiq::Client,
+         ::Gitlab::SidekiqMiddleware::DuplicateJobs::Client,
+         ::Gitlab::SidekiqStatus::ClientMiddleware,
+         ::Gitlab::SidekiqMiddleware::AdminMode::Client,
+         ::Gitlab::SidekiqMiddleware::ClientMetrics
       ]
     end