Add ci_destroy_all_expired_service feature flag

Add an extra flag to completely shut off the worker, so we can
effectively turn off artifact expiration quickly and without any
infra configuration changes.

app/services/ci/job_artifacts/destroy_all_expired_service.rb

@@ -26,6 +26,8 @@ module Ci
       # preventing multiple `ExpireBuildArtifactsWorker` CRON jobs run concurrently,
       # which is scheduled every 7 minutes.
       def execute
+        return 0 unless ::Feature.enabled?(:ci_destroy_all_expired_service, default_enabled: :yaml)
+
         in_lock(EXCLUSIVE_LOCK_KEY, ttl: LOCK_TIMEOUT, retries: 1) do
           if ::Feature.enabled?(:ci_destroy_unlocked_job_artifacts)
             destroy_unlocked_job_artifacts

config/feature_flags/development/ci_destroy_all_expired_service.yml

+---
+name: ci_destroy_all_expired_service
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/76504
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/348786
+milestone: '14.6'
+type: development
+group: group::pipeline execution
+default_enabled: false