fix: scaffold tuf secrets path in default values.yaml

[falcorocks]

Description of the change

Tuf chart has been updated to version 0.1.9 to resolve a bug in the default path of sigstore PKI secrets (links below). Tuf new version has been updated in the scaffold chart, however the default values of the scaffold chart were not updated. This PR fixes the default value (which otherwise override the previous fix, unless one knows about it :)

Existing or Associated Issue(s)

• closes scaffold chart default values need to be updated to fix tuf secrets names mismatch #678
• also relates to:
  • ctfe public key default name breaks cosign scaffolding#873
  • Path in deployed CTFE public key file for ephemeral TUF creation should include "ctfe" to correctly hint as to its use in TUF creation #670

Additional Information

Checklist

• Chart version bumped in Chart.yaml according to semver. Where applicable, update and bump the versions in any associated umbrella chart
• Variables are documented in the values.yaml and added to the README.md. The helm-docs utility can be used to generate the necessary content. Use helm-docs --dry-run to preview the content.
• JSON Schema generated.
• List tests pass for Chart using the Chart Testing tool and the ct lint command.