Container builds fail when host is configured for cgroups v2

Current version of crun doesn't play well with nested containers under cgroups v2. https://gitlab.com/ModioAB/base-image/-/pipelines/575595062

Probable cause is fixed on upstream main, but no known release yet. https://github.com/containers/crun/pull/931

Alternative paths to work around.

• Don't use sub-cgroups in the in-container container !113 (closed)
• Switch back to runc for now !112 (merged)