Update the Helm chart to consume the plugin catalog index OCI artifact by setting the CATALOG_INDEX_IMAGE environment variable in the install-dynamic-plugins init container.

Acceptance criteria:

• CATALOG_INDEX_IMAGE environment variable is set in install-dynamic-plugins init container

• catalogIndex configuration exists in values.yaml with enabled and image fields
• values.schema.json validates catalogIndex configuration
• Test Users can override catalogIndex.image value
• Helm chart renders correctly with default values