Do not stick runner to primary database after tick

config/feature_flags/development/ci_runner_builds_queue_on_replicas.yml

+---
+name: ci_runner_builds_queue_on_replicas
+introduced_by_url: 
+rollout_issue_url: 
+milestone: '13.10'
+type: development
+group: group::continuous integration
+default_enabled: false

ee/app/models/ee/ci/runner.rb

@@ -6,7 +6,9 @@ module EE
       extend ActiveSupport::Concern
 
       def tick_runner_queue
-        ::Gitlab::Database::LoadBalancing::Sticking.stick(:runner, id)
+        unless Feature.enabled?(:ci_runner_builds_queue_on_replicas, runner, default_enabled: :yaml)
+          ::Gitlab::Database::LoadBalancing::Sticking.stick(:runner, id)
+        end
 
         super
       end