Permit users to configure pages `expire_in` in gitlab-ci.yml
### Problem Since we have [limits](https://gitlab.com/gitlab-org/gitlab/-/issues/442947) on how many active extra deployments a namespace/project might have, we need a way to enable the users to delete extra deployments to increase their availability. ### Proposed solution Permit users to configure pages version `expire_in` in gitlab-ci.yml, similar to [artifacts](https://docs.gitlab.com/ee/ci/yaml/#artifactsexpire_in)
issue