Add the ExclusiveLeaseGuard concern

What does this MR do?

Are there points in the code the reviewer needs to double check?

This needs an EE too, to move ee/app/services/concerns/exclusive_lease_guard.rb to app/services/concerns/exclusive_lease_guard.rb.

Why was this MR needed?

Files containing try_obtain:

• app/models/concerns/reactive_caching.rb (I don't want to mix one concern into the other)
• app/models/user.rb (used differently)
• app/workers/background_migration_worker.rb (used differently)
• app/workers/propagate_service_template_worker.rb
• app/workers/gitlab_usage_ping_worker.rb
• app/workers/repository_check/batch_worker.rb
• app/workers/project_migrate_hashed_storage_worker.rb
• app/workers/stuck_ci_jobs_worker.rb
• app/workers/git_garbage_collect_worker.rb (used differently)
• app/workers/project_cache_worker.rb
• app/workers/check_gcp_project_billing_worker.rb
• app/controllers/application_controller.rb (used differently)
• app/services/projects/housekeeping_service.rb (used differently)
• app/services/users/refresh_authorized_projects_service.rb (used differently)
• app/services/keys/last_used_service.rb (used differently)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• [-] API support added
• Tests added for this feature/bug
• Review
  • [-] Has been reviewed by UX
  • [-] Has been reviewed by Frontend
  • Has been reviewed by Backend
  • [-] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes gitlab-org/gitlab-ce#39750.

EE MR in gitlab-org/gitlab-ee!5017