[8.x](backport #2824) Update serverless workflow to use correct stack version

[mergify]

Summary of your changes

This PR updates the stack version used for installing integrations in the serverless environment and fixes the installation of agentless integration for GCP, which was missing the project ID. Additionally, support for saving the state of agentless agents has been added to ensure proper enrollment verification.

Tests

Successful workflow run

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This is an automatic backport of pull request #2824 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of a03de6f has failed:

On branch mergify/bp/8.x/pr-2824
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit a03de6f.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   .github/workflows/weekly-serverless.yml
	modified:   tests/integrations_setup/configuration_fleet.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   tests/integrations_setup/install_agentless_integrations.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b mergify/bp/8.x/pr-2824 upstream/mergify/bp/8.x/pr-2824
git merge upstream/8.x
git push upstream mergify/bp/8.x/pr-2824