Enhance CA chain logging and error handling

[Syoc]

I'm having issues troubleshooting 404 issues with the cert/ca endpoint.
Vault returns "Failed to fetch CA list from EJBCA" and a 404 request to "https://my-domain.com/ejbca/ejbca-rest-api/v1/ca//certificate/download".
Reading the code makes it look like the caName match here never hits.

More logging with results from the ListCas endpoint would make this issue easier to debug.

I also makes more sense to me to error out if the for loop completes without a caName match instead of requesting a certificate for empty string.

Running vault version 1.16.3 and plugin version 1.4.0.

[svenska-primekey]

The caName needs to match the friendly name created in EJBCA. If the CA name is ManagementCA you would use ManagementCA for the EJBCA vault config.

Thank you for the feedback. We will take a look and see what we can do.