Introduce Cells claims verification workers and cron scheduling

What does this MR do and why?

• Add Cells::ClaimsVerificationWorker to run verification per model, gated by a dynamic ops feature flag per model name. This worker calls Cells::Claims::VerificationService introduced in !226233 (merged), to backfill and reconcile changes between Rails and Topology Service.
• Add Cells::ScheduleClaimsVerificationWorker as a cron job that enqueues a ClaimsVerificationWorker for every model registered via Cells::Claimable with 10 mins delay. This cronjob runs once every Saturdays, and the schedule is randomized between 00:00 to 23:59 to avoid thunderring herd from all cells running this worker. This is done via Gitlab::Scheduling::ScheduleWithinWorker

References

gitlab-com/gl-infra/tenant-scale/cells-infrastructure/team#468

How to set up and validate locally

1. In console, run Rails.application.eager_load! to ensure all models have been loaded

2. Enable the feature flags:

    %w[
       cells_claims_verification_worker_organizations_organization
       cells_claims_verification_worker_project
       cells_claims_verification_worker_namespace
       cells_claims_verification_worker_user
       cells_claims_verification_worker_key
       cells_claims_verification_worker_email
       cells_claims_verification_worker_gpg_key
       cells_claims_verification_worker_redirect_route
       cells_claims_verification_worker_route
       cells_claims_verification_worker_service_desk_setting
     ].each { |flag| Feature.enable(flag) }

3. Run the Cells::ScheduleClaimsVerificationWorker

   Cells::ScheduleClaimsVerificationWorker.new.perform

4. Check that the claims records are backfilled in topology service database:

   gdk psql -d topology_service
   
   SELECT * FROM claims;

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.