[8.x](backport #41822) [xpack][metricbeats][gcp] don't skip first value in histogram calculations

[mergify]

Proposed commit message

Don't skip first value in histogram upper bound calculations.

This should be done because according to GCP doc (https://cloud.google.com/monitoring/api/ref_v3/rpc/google.api) the histogram (Exponential and Linear) upper bound should include bucket values at index 0.

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.

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

Related issues

Closes #

Use cases

Screenshots

Here is screenshot from local test - values seem to be ok

Logs

---

This is an automatic backport of pull request #41822 done by [Mergify](https://mergify.com).

[botelastic]

This pull request doesn't have a Team:<team> label.

[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-41822 upstream/mergify/bp/8.x/pr-41822
git merge upstream/8.x
git push upstream mergify/bp/8.x/pr-41822

[shmsr]

@gpop63 / @stefans-elastic is it not needed in 8.x branch??

[stefans-elastic]

@gpop63 / @stefans-elastic is it not needed in 8.x branch??

my bad, let me fix and merge this PR