Delete self monitoring project related services and specs

Relevant files

• app/services/metrics/dashboard/self_monitoring_dashboard_service.rb
• spec/requests/self_monitoring_project_spec.rb
• spec/services/metrics/dashboard/self_monitoring_dashboard_service_spec.rb
• spec/support/shared_examples/requests/self_monitoring_shared_examples.rb
• spec/support/shared_examples/workers/self_monitoring_shared_examples.rb