Persistent Volume Claims should be regularly cleaned up for Review Apps

I found out in https://gitlab.com/gitlab-org/quality/team-tasks/issues/212#note_214686148 that Gitaly persistent volume claims aren't cleaned up after a Review App is deleted.

This is an expected behavior (gitlab-org/charts/gitlab#1538 (comment 207559145)) but leave a lot of unused persistent volume claims in our clusters (as can be seen in https://gitlab.com/gitlab-org/quality/team-tasks/issues/212#note_214686148).

We should clean the persistent volume claims regularly similarly to how we regularly cleanup the Review App and deployments/environments, see https://docs.gitlab.com/ee/development/testing_guide/review_apps.html#detailed-explanation.