[7.17](backport #40207) Change SQS metrics statistic method

[mergify]

Proposed commit message

This PR is to fix statistic method applied to diff metrics in SQS metricset from aws module. This change has been done in elastic/integrations#8521 but didn't make it in Beats.

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

It will not, because rename processor renamed all the fields from sqs metricset already. Users need to pay attention to the documentation change on the field description. But dashboards will not be broken.

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This is an automatic backport of pull request #40207 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 918edab has failed:

On branch mergify/bp/7.17/pr-40207
Your branch is up to date with 'origin/7.17'.

You are currently cherry-picking commit 918edab6b8.
  (fix conflicts and run "git cherry-pick --continue")
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   CHANGELOG.next.asciidoc
	modified:   metricbeat/docs/fields.asciidoc
	modified:   x-pack/metricbeat/module/aws/sqs/_meta/fields.yml
	modified:   x-pack/metricbeat/module/aws/sqs/manifest.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   x-pack/metricbeat/module/aws/fields.go

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

[botelastic]

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