[GCP] Group metrics by dimensions

[zmoog]

With this change I expect the metricset will group together the metrics from the same resource having the same dimension values.

What does this PR do?

Why is it important?

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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Related issues

• Relates [GCP] Metrics are not grouped by dimension integrations#6568

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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 @zmoog? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
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To fixup this pull request, you need to add the backport labels for the needed
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• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

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• Start Time: 2023-06-22T08:11:28.164+0000

• Duration: 50 min 1 sec

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Test	Results
Failed	0
Passed	1533
Skipped	90
Total	1623

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[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 zmoog/gcp-metrics-grouping upstream/zmoog/gcp-metrics-grouping
git merge upstream/main
git push upstream zmoog/gcp-metrics-grouping

[zmoog]

Replaced by #36682.