Disable Rails SQL query cache when applying service templates

When the SQL query cache is active, the SELECT query for finding
projects to apply service templates returns the same values. This causes
an infinite loop because even though bulk INSERT queries are made, the
cached results never reflect that progress.  To fix this, we call
`Project.uncached` around the query to ensure new data is retrieved.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/63595

app/services/projects/propagate_service_template.rb

@@ -24,7 +24,7 @@ module Projects
 
     def propagate_projects_with_template
       loop do
-        batch = project_ids_batch
+        batch = Project.uncached { project_ids_batch }
 
         bulk_create_from_template(batch) unless batch.empty?
 

changelogs/unreleased/sh-service-template-bug.yml

+---
+title: Disable Rails SQL query cache when applying service templates
+merge_request: 30060
+author:
+type: fixed

spec/services/projects/propagate_service_template_spec.rb

@@ -72,7 +72,7 @@ describe Projects::PropagateServiceTemplate do
       expect(project.pushover_service.properties).to eq(service_template.properties)
     end
 
-    describe 'bulk update' do
+    describe 'bulk update', :use_sql_query_cache do
       let(:project_total) { 5 }
 
       before do

spec/spec_helper.rb

@@ -218,6 +218,12 @@ RSpec.configure do |config|
     ActionController::Base.cache_store = caching_store
   end
 
+  config.around(:each, :use_sql_query_cache) do |example|
+    ActiveRecord::Base.cache do
+      example.run
+    end
+  end
+
   # The :each scope runs "inside" the example, so this hook ensures the DB is in the
   # correct state before any examples' before hooks are called. This prevents a
   # problem where `ScheduleIssuesClosedAtTypeChange` (or any migration that depends