add missing tests for DekRegistry

[jeff-cf]

What

Checklist

• Contains customer facing changes? Including API/behavior changes No
• Is this change gated behind feature flag(s)? Not needed
  • List the LD flags needed to be set to enable this change
• Did you add sufficient unit test and/or integration test coverage for this PR? Yes
  • If not, please explain why it is not required
• Does this change require modifying existing system tests or adding new system tests? No
  • If so, include tracking information for the system test changes

References

JIRA: DGS-19622

Test & Review

This is to add tests.

Open questions / Follow-ups

[confluent-cla-assistant]

🎉 All Contributor License Agreements have been signed. Ready to merge.
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

[sonarqube-confluent]

Analysis Details

4 Issues

• 0 Bugs
• 0 Vulnerabilities
• 4 Code Smells

Coverage and Duplications

• No coverage information (72.70% Estimated after merge)
• No duplication information (2.20% Estimated after merge)

Project ID: schema-registry

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