[9.0] (backport #8377) [CI] BK Vault plugin for EC access

[mergify]

What does this PR do?

Introduces BK Vault plugin. Simplifies EC access and prevents possible issues
Windows retry tested in this build

Why is it important?

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

How to test this PR locally

Related issues

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?
• ...

---

This is an automatic backport of pull request #8377 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of e2505e4 has failed:

On branch mergify/bp/9.0/pr-8377
Your branch is up to date with 'origin/9.0'.

You are currently cherry-picking commit e2505e453.
  (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:   .buildkite/bk.integration.pipeline.yml
	modified:   .buildkite/hooks/pre-command
	modified:   .buildkite/scripts/steps/ess.ps1
	modified:   .buildkite/scripts/steps/ess.sh

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   .buildkite/bk.integration-fips.pipeline.yml

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

[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

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 57caa5a

cc @pazone