[8.18](backport #6805) [ci] disable kubernetes_secrets unit-test on windows that relies on timing

[mergify]

What does this PR do?

For the same reason, as the one captured here, this PR disables timing-based unit-test for kubernetes_secrets provider on Windows platform

Why is it important?

Because we need our CI to be green and timing-based unit-tests on windows are proven to be flaky

Checklist

• I have read and understood the pull request guidelines of this project.
• 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
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Disruptive User Impact

N/A

How to test this PR locally

N/A

Related issues

N/A

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This is an automatic backport of pull request #6805 done by Mergify.

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube