:seedling: Align ClusterObjectSet e2e cleanup with addedResources pattern (#2799)

Track ClusterObjectSets in addedResources when applied, matching
the pattern established for ClusterExtensions in #2783. This removes
the special-case cleanup block in ScenarioCleanup and ensures multiple
ClusterObjectSets per scenario are all cleaned up correctly.

Co-authored-by: Per G. da Silva <pegoncal@redhat.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>