chore: add large lag threshold test for Kafka scalers

[dttung2905]

Hi team,

I'm adding a new test case from my investigation here.

Checklist

• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• Changelog has been updated and is aligned with our changelog requirements
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Relates to #5354

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[dttung2905]

btw PR Welcome Bot is failing 🤔

1s
Run actions/github-script@60a0d83039c74a4aee543508d2ffcb[1](https://github.com/kedacore/keda/actions/runs/7495198848/job/20404789645?pr=5361#step:3:1)c3799cdea
  with:
    github-token: ***
    script: await github.rest.issues.createComment({
    owner: context.repo.owner,
    repo: context.repo.repo,
    issue_number: ,
    body: 'Thank you for your contribution! 🙏 We will review your PR as soon as possible.\n\n\n While you are waiting, make sure to:\n\n\n- Add an entry in [our changelog](https://github.com/kedacore/keda/blob/main/CHANGELOG.md) in alphabetical order and link related issue\n- Update the [documentation](https://github.com/kedacore/keda-docs), if needed\n- Add unit & [e[2](https://github.com/kedacore/keda/actions/runs/7495198848/job/20404789645?pr=5361#step:3:2)e](https://github.com/kedacore/keda/blob/main/tests/README.md) tests for your changes\n- GitHub checks are passing\n- Is the DCO check failing? Here is [how you can fix DCO issues](https://github.com/kedacore/keda/blob/main/CONTRIBUTING.md#i-didnt-sign-my-commit-now-what)\n\n\nLearn more about:\n- Our [contribution guide](https://github.com/kedacore/keda/blob/main/CONTRIBUTING.md)'
  });
  
    debug: false
    user-agent: actions/github-script
    result-encoding: json
    retries: 0
    retry-exempt-status-codes: 400,401,40[3](https://github.com/kedacore/keda/actions/runs/7495198848/job/20404789645?pr=5361#step:3:3),[4](https://github.com/kedacore/keda/actions/runs/7495198848/job/20404789645?pr=5361#step:3:4)04,422
SyntaxError: Unexpected token ','
    at new AsyncFunction (<anonymous>)
Error: Unhandled error: SyntaxError: Unexpected token ','

I think probably because of this PR #5365 . Let me try to rebase from master

[zroubalik]

LGTM, thanks!