fix(admin): certificates page infinite loading fix

Description

fix(admin): certificates page infinite loading fix

• fixed a bug where the user certificates table would never load
• correctly pass the retrieved attribute to the attributes list component
• added a text in case the underlying certificates attribute does not exist, this should not happen however

How to test

Visit the certificates page of any service account (e.g. /myProfile/service-identities/134146/authentication/certificates) and see that it works.

Author's checklist

• I have followed the contribution guidelines
• This MR has been tested or does not change functionality
• I have added relevant merge request dependencies (if this MR has any)
• I have added the correct labels
• I have assigned reviewers (if any are relevant)
• I have edited the documentation (if the changes require it) or I have noted the need for the change if I do not have access to the documentation
• I have marked all introduced BREAKING CHANGES or necessary DEPLOYMENT NOTES in the commit message(s)

Reviewer's checklist

• This MR has been tested or does not change functionality
• This MR has correct commit message format

Other information

Also added some text in case the certificates attribute doesn't exist. In this case there has been an issue with the instance, since the attribute should be always created.

Related issues

Closes STR-1526