Merge branch 'test-db-load-balance' into 'master'

Speed up CI job `rspec frontend_fixture` by skipping database load balancing

See merge request gitlab-org/gitlab!71212

.gitlab/ci/frontend.gitlab-ci.yml

@@ -115,6 +115,8 @@ update-storybook-yarn-cache:
   needs: ["setup-test-env", "retrieve-tests-metadata", "compile-test-assets"]
   variables:
     WEBPACK_VENDOR_DLL: "true"
+    GITLAB_NO_AR_DB_PREPEND_LOAD_BALANCING: "true"
+    GITLAB_USE_PREPARED_STATEMENTS: "true"
   script:
     - run_timed_command "gem install knapsack --no-document"
     - run_timed_command "scripts/gitaly-test-spawn"

config/initializers/load_balancing.rb

@@ -2,7 +2,7 @@
 
 ActiveRecord::Base.singleton_class.attr_accessor :load_balancing_proxy
 
-Gitlab::Database.main.disable_prepared_statements
+Gitlab::Database.main.disable_prepared_statements unless ENV['GITLAB_USE_PREPARED_STATEMENTS'] == 'true'
 
 Gitlab::Application.configure do |config|
   config.middleware.use(Gitlab::Database::LoadBalancing::RackMiddleware)
@@ -11,7 +11,7 @@ end
 # This hijacks the "connection" method to ensure both
 # `ActiveRecord::Base.connection` and all models use the same load
 # balancing proxy.
-ActiveRecord::Base.singleton_class.prepend(Gitlab::Database::LoadBalancing::ActiveRecordProxy)
+ActiveRecord::Base.singleton_class.prepend(Gitlab::Database::LoadBalancing::ActiveRecordProxy) unless ENV['GITLAB_NO_AR_DB_PREPEND_LOAD_BALANCING'] == 'true'
 
 # The load balancer needs to be configured immediately, and re-configured after
 # forking. This ensures queries that run before forking use the load balancer,