Add production fixture to create project

Since migrations are not run by new instances, add a production
fixture that should ensure that the self-monitoring project is created
for new instances as well.

db/fixtures/development/98_gitlab_instance_administration_project.rb

+# frozen_string_literal: true
+
+::Gitlab::DatabaseImporters::SelfMonitoring::Project::CreateService.new.execute!

db/fixtures/production/998_gitlab_instance_administration_project.rb

+# frozen_string_literal: true
+
+::Gitlab::DatabaseImporters::SelfMonitoring::Project::CreateService.new.execute!