Add encoded/non-encoded auth method to xpack unit tests

[alexcams]

Release notes

ES Logstash configuration should support encoded and non-encoded api-key formats.

What does this PR do?

Since the http client used for Centrilized Pipeline Management and Stack Monitoring is the one implemented at EX Output plugin as we can see here, and it has been already published, no changes are needed in logstash core code to support both api-key formats.
This PR includes unit tests to prevent future regressions if the plugin client is changed.

Why is it important/What is the impact to the user?

User is now able to use both api-key formats.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Related issues

• Closes #18096 and #18095

[github-actions]

🤖 GitHub comments

Expand to view the GitHub comments

Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[mergify]

This pull request does not have a backport label. Could you fix it @alexcams? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• If no backport is necessary, please add the backport-skip label

[Copilot]

Pull Request Overview

Adds unit tests to ensure both encoded and non-encoded api_key formats are accepted for xpack management Elasticsearch source initialization.

• Introduces parameterized test contexts for non-encoded and Base64-encoded api_key values.
• Verifies initialization does not raise errors with either api_key format.

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: e866999

History

• 💛 Build #3696 was flaky f38b924

[github-actions]

@Mergifyio backport 9.0 9.1 9.2

[mergify]

backport 9.0 9.1 9.2

✅ Backports have been created

• #18323 [9.0] (backport #18307) Add encoded/non-encoded auth method to xpack unit tests has been created for branch 9.0
• #18324 [9.1] (backport #18307) Add encoded/non-encoded auth method to xpack unit tests has been created for branch 9.1
• #18325 [9.2] (backport #18307) Add encoded/non-encoded auth method to xpack unit tests has been created for branch 9.2