refactor: migrate xdg/scram usage to xdg-go/scram

[kruskall]

Proposed commit message

From the repo readme:

DON'T USE THIS PACKAGE - use xdg-go/scram instead!

I renamed this to xdg-go/scram in October 2018. This didn't break dependencies at the time because Github redirected requests. In March 2021, I made xdg-go/scram a module, which can't be used as xdg/scram with Github redirects. This repository has been recreated to support legacy dependencies.

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.next.asciidoc or CHANGELOG-developer.next.asciidoc.

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[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @kruskall? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

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

[kruskall]

run docs-build