Cleanup floating IPs

Currently, temporary floating IPs are only cleaned up in stop_review job in merge request pipeline at .gitlab-ci.yml#L397. That's assuming the pipeline didn't fail earlier and make it through deploying a review app and later stopped either automatically or manually.

When developing new feature, a lot of times the pipeline doesn't even make it through deploying a review app, and that leaves some lingering floating IPs. Therefore, I want to create script to delete those supposed to be temporary floating IPs in cleanup stage.

My proposed way of doing this in cheaha-cloud project is to query floating Ips with:

openstack floating ip list --not-any-tags reserved --status DOWN

This approach assumes we have those "static" floating IPs tagged with reserved.

Tagging floating IPs doesn't seem to be supported via WebUI so it does add an additional step to create a "static" floating Ip in the future.