[fix] skip API GW stage certyficates when `ClientCertificateId` is ni…

[wakeful]

Description

Fixes #739

TODOs

Read the Gruntwork contribution guidelines.

• [x] Update the docs.
• [x] Run the relevant tests successfully, including pre-commit checks.
• [x] Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• [x] Include release notes. If this PR is backward incompatible, include a migration guide.
• [ ] Attention Grunts - if this PR adds support for a new resource, ensure the nuke_sandbox and nuke_phxdevops jobs in .circleci/config.yml have been updated with appropriate exclusions (either directly in the job or via the .circleci/nuke_config.yml file) to prevent nuking IAM roles, groups, resources, etc that are important for the test accounts.

Release Notes (draft)

Fix panic when deleting API GW stage certificate for AWS mng domains.

Migration Guide

n/a

[james03160927]

Passed all the tests https://app.circleci.com/pipelines/github/gruntwork-io/cloud-nuke/15198/workflows/04226403-1782-41f6-acb9-06d7d76c98c4.

Thanks for making this change.