Add support for additional praefect tests

Allows tests to be run that require Praefect to be configured as a repository storage.

The Praefect scenario has Praefect configured as the default storage, so it can run such tests. They can also run on Staging or other environments, provided QA_PRAEFECT_REPOSITORY_STORAGE is set appropriately.

Part of https://gitlab.com/gitlab-org/quality/testcases/-/issues/276

Depends on https://gitlab.com/gitlab-org/gitlab/-/merge_requests/27295. Both MRs should be merged and released together.