[AWS] Add include_linked_accounts config parameter for ListMetrics API

[kaiyan-sheng]

What does this PR do?

This PR is to add include_linked_accounts config parameter into aws module. Default is true for this config so metrics from linked accounts will always be collected. Default is false

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.

Related issues

• Relates [AWS] Add support for collecting metrics from linked cloudwatch accounts using cross-account monitoring  integrations#6253

How to test it

1. Test without include_linked_accounts config and by default (false) we should not collect any metrics from linked accounts.
2. Test with include_linked_accounts = false config and we should not collect any metrics from linked accounts.
3. Test with include_linked_accounts = true config and we should see metrics from all linked accounts.

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @kaiyan-sheng? 🙏.
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]

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• Start Time: 2023-06-02T19:41:21.551+0000

• Duration: 92 min 37 sec

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Test	Results
Failed	0
Passed	4658
Skipped	1022
Total	5680

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[girodav]

Made some changes directly on the PR to speed things up. Thanks for this Kaiyan :)

[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 add_include_linked_accounts upstream/add_include_linked_accounts
git merge upstream/main
git push upstream add_include_linked_accounts

[cmacknz]

Approving the config and docs changes.

[andresrc]

I think we can remove the backport to 8.7