[9.1](backport #47663) test(TestGenerateProcessorList): close processor before return

[mergify[bot]]

Proposed commit message

close the processors to ensure graceful shutdown and avoid goroutine leak.

use logptest logger in test

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
• [ ] I have added tests that prove my fix is effective or that my feature works. Where relevant, I have used the stresstest.sh script to run them under stress conditions and race detector to verify their stability.
• [ ] I have added an entry in ./changelog/fragments using the changelog tool.

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

• Closes https://github.com/elastic/beats/issues/47528
• Requires https://github.com/elastic/beats/pull/47661 and https://github.com/elastic/beats/pull/47662 to completely fix the leak

Use cases

Screenshots

Logs

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This is an automatic backport of pull request #47663 done by [Mergify](https://mergify.com).

[github-actions[bot]]

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[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)

[mergify[bot]]

This pull request has not been merged yet. Could you please review and merge it @kruskall? 🙏