Add Win 10 && 11 to elastic-agent bk.integration pipeline

[oakrizan]

What does this PR do?

Added integration test steps for Windows 10 && 11 in bk.integration.pipeline.yml
Buildkite buikds: https://buildkite.com/elastic/elastic-agent-extended-testing-bk/builds?branch=add-win-desktop-to-bk-integration

Why is it important?

Allows to run IT tests separately and initiate independent restarts, granularly run tests and optimize the tests duration

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
• I have added an entry in ./changelog/fragments using the changelog tool
• I have added an integration test or an E2E test

Related issues

• Relates: https://github.com/elastic/ingest-dev/issues/4219

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

[mergify]

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

• backport-./d./d is the label to automatically backport to the 8./d branch. /d is the digit

[mergify]

backport-v8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label and remove the backport-8.x label.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[pazone]

I'm not sure that we have to enable Windows desktop integration tests right now. Let's hold the PR until we decide on it