Merge branch '300003-pages-migration-threads-fail-sometimes' into 'master'

Fix pages migration threads

See merge request gitlab-org/gitlab!52571

app/models/project_pages_metadatum.rb

@@ -11,5 +11,5 @@ class ProjectPagesMetadatum < ApplicationRecord
 
   scope :deployed, -> { where(deployed: true) }
   scope :only_on_legacy_storage, -> { deployed.where(pages_deployment: nil) }
-  scope :with_project_route_and_deployment, -> { preload(project: [:namespace, :route, pages_metadatum: :pages_deployment]) }
+  scope :with_project_route_and_deployment, -> { preload(:pages_deployment, project: [:namespace, :route]) }
 end

app/services/pages/migrate_from_legacy_storage_service.rb

@@ -32,8 +32,10 @@ module Pages
     def start_migration_threads
       Array.new(@migration_threads) do
         Thread.new do
-          while batch = @queue.pop
-            process_batch(batch)
+          Rails.application.executor.wrap do
+            while batch = @queue.pop
+              process_batch(batch)
+            end
           end
         end
       end