Changes:
- Updated the error logged in `register-one-fleet-instance-using-vpp`
action when a Fleet license key cannot be verified to include the
error's message.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved error reporting when Fleet license verification fails,
providing more specific details to support troubleshooting.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Eric
c681fcb9fb