Add data consistency for UpdateAllMirrorsWorker

This worker doesn't perform SQL writes, we can request
replicas instead of primary

config/feature_flags/development/load_balancing_for_update_all_mirrors_worker.yml

+---
+name: load_balancing_for_update_all_mirrors_worker
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64526
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/334162
+milestone: '14.1'
+type: development
+group: group::source code
+default_enabled: false

ee/app/workers/update_all_mirrors_worker.rb

@@ -7,6 +7,7 @@ class UpdateAllMirrorsWorker # rubocop:disable Scalability/IdempotentWorker
   include CronjobQueue
 
   feature_category :source_code_management
+  data_consistency :sticky, feature_flag: :load_balancing_for_update_all_mirrors_worker
 
   LEASE_TIMEOUT = 5.minutes
   SCHEDULE_WAIT_TIMEOUT = 4.minutes

ee/spec/workers/update_all_mirrors_worker_spec.rb

@@ -11,6 +11,11 @@ RSpec.describe UpdateAllMirrorsWorker do
     stub_exclusive_lease
   end
 
+  it_behaves_like 'worker with data consistency',
+                  described_class,
+                  feature_flag: :load_balancing_for_update_all_mirrors_worker,
+                  data_consistency: :sticky
+
   describe '#perform' do
     it 'does nothing if the database is read-only' do
       allow(Gitlab::Database).to receive(:read_only?).and_return(true)