Delete self monitoring project workers and their usages

Relevant files

backend

• app/workers/self_monitoring_project_create_worker.rb
• app/workers/self_monitoring_project_delete_worker.rb
• spec/workers/self_monitoring_project_delete_worker_spec.rb
• spec/workers/self_monitoring_project_create_worker_spec.rb
• app/workers/concerns/self_monitoring_project_worker.rb
• config/prometheus/self_monitoring_default.yml

Any other files for usages of this above classes should be updated too.