DGS-22736 Add support for DELETE /mode

[karthikeyanas]

What

Currently DELETE /mode is not supported which prevent us for resetting the mode set using PUT /mode. This change add support for DELETE /mode

Checklist

Please answer the questions with Y, N or N/A if not applicable.

• [Y] Contains customer facing changes? Including API/behavior changes
• [N] Is this change gated behind config(s)?
  • List the config(s) needed to be set to enable this change
• [Y] Did you add sufficient unit test and/or integration test coverage for this PR?
  • If not, please explain why it is not required
• [N] Does this change require modifying existing system tests or adding new system tests?
  • If so, include tracking information for the system test changes
• [N] Must this be released together with other change(s), either in this repo or another one?
  • If so, please include the link(s) to the changes that must be released together

References

JIRA: https://confluentinc.atlassian.net/browse/DGS-22736

Test & Review

• Integration tests.
• Manual validation

[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.}

[sonarqube-confluent]

• 0.00% Coverage on New Code (is less than 80.00%)

Analysis Details

45 Issues

• 3 Bugs
• 0 Vulnerabilities
• 42 Code Smells

Coverage and Duplications

• 0.00% Coverage (0.00% Estimated after merge)
• No duplication information (2.10% Estimated after merge)

Project ID: schema-registry

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