:seedling: Add e2e regression test for cross-CE collision protection (#2783)

- Add e2e test verifying that a second ClusterExtension targeting an
  already-installed bundle cannot take over resources from the original
  owner, even with a higher-revision ClusterObjectSet. The single
  merged scenario covers both initial collision detection after an
  upgrade and collision persistence across revisions.
- Use ${NAME} / ${NAME}-dup naming convention in the collision scenario
  so CE names stay abstract. Stop overwriting sc.clusterExtensionName
  in ResourceIsApplied so ${NAME} remains constant throughout a
  scenario — the overwrite was always a no-op for existing tests since
  they all use name: ${NAME}.
- Auto-track every applied ClusterExtension for cleanup via
  addedResources in ResourceIsApplied, eliminating the manual
  TrackCurrentClusterExtensionForCleanup step and the redundant
  sc.clusterExtensionName cleanup in ScenarioCleanup.
- Add named CE condition steps (NamedClusterExtensionReportsCondition,
  NamedClusterExtensionReportsConditionWithMessageFragment) so step
  descriptions explicitly identify which CE is being asserted.
- Add ClusterExtensionOwnsClusterObjectSets step to verify the number
  of ClusterObjectSets owned by a named CE.
- Extract messageFragmentComparison helper to deduplicate the
  fragment-matching closure across condition steps.
- Preserve unresolved template variables as literal ${KEY} instead of
  silently substituting empty string.

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