Remove FKs from partitioned tables of ci_runner_machines_687967fa8a

In gitlab-com/gl-infra/production#18796 (closed), we dropped the fk_rails_3f92913d27 FK from the CI database in order to mitigate the gitlab-com/gl-infra/production#18792 (closed) incident. We now need to deploy a migration that will remove the FKs from the 3 partitions in both databases, in case they exists, so that the schema is consistent between databases in .com, and for self-managed users.