Cleanup deprecation for v2.13 release

[dttung2905]

Provide a description of what has been changed
Hi team,

I create this PR to clean up the deprecation for v2.13

Checklist

• I have verified that my change is according to the deprecations & breaking changes policy
• Changelog has been updated and is aligned with our changelog requirements
• A PR is opened to update the documentation on (repo) clean up documentation for 2.13 deprecation release keda-docs#1240
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Fixes #5051

[github-actions]

Thank you for your contribution! 🙏 We will review your PR as soon as possible.

While you are waiting, make sure to:

• Add an entry in our changelog in alphabetical order and link related issue
• Update the documentation, if needed
• Add unit & e2e tests for your changes
• GitHub checks are passing
• Is the DCO check failing? Here is how you can fix DCO issues

Learn more about:

• Our contribution guide

[JorTurFer]

@zroubalik @tomkerkhove , can we remove these things? I'd like to prevent last release doubts before merging.
These are the deprecations:

• Deprecate tlsCertFile in external scaler in favour of mor fine-grained config #4549
• Remove Azure Data Explorer 'metadata.clientSecret' #4514

Both modifies trigger spec, so in theory we are modifying the CRD and we aren't allowed as we discussed last time. Despite of that, I'd go ahead with at least the removal of the secret from trigger.metadata because it has security implications

[zroubalik]

@zroubalik @tomkerkhove , can we remove these things? I'd like to prevent last release doubts before merging. These are the deprecations:

* [Deprecate `tlsCertFile` in external scaler in favour of mor fine-grained config #4549](https://github.com/kedacore/keda/issues/4549)

* [Remove Azure Data Explorer 'metadata.clientSecret' #4514](https://github.com/kedacore/keda/issues/4514)

Both modifies trigger spec, so in theory we are modifying the CRD and we aren't allowed as we discussed last time. Despite of that, I'd go ahead with at least the removal of the secret from trigger.metadata because it has security implications

I agree.

[JorTurFer]

LGTM!
Thanks! 🙇

[JorTurFer]

/run-e2e azure
Update: You can check the progress here