Services: code style fixes, minor refactoring

app/services/audit_event_service.rb

...ervices/auth/container_registry_authentication_service.rb

app/services/create_branch_service.rb

app/services/create_release_service.rb

app/services/create_snippet_service.rb

app/services/create_tag_service.rb

app/services/delete_branch_service.rb

app/services/delete_tag_service.rb

app/services/files/base_service.rb

app/services/files/create_service.rb

app/services/git_tag_push_service.rb

app/services/issues/bulk_update_service.rb

app/services/merge_requests/post_merge_service.rb

app/services/notification_service.rb

app/services/projects/update_service.rb

app/services/system_note_service.rb

app/services/update_release_service.rb

app/services/update_snippet_service.rb