[8.x](backport #41099) [aws] Change log.file.path field in awscloudwatch input to nested object

[mergify]

Proposed commit message

This PR changes log.file.path field in awscloudwatch input from dotted field to nested object.

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

The concern we have with this PR is when users have ingest pipelines or logstash filters configured down the line, this might break what they have. For example in ingest pipeline, ctx[‘log.file.path’] needs to be changed to ctx.log?.file?.path.

---

This is an automatic backport of pull request #41099 done by Mergify.

[mergify]

Cherry-pick of 904d14b has failed:

On branch mergify/bp/8.x/pr-41099
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Changes to be committed:
	modified:   CHANGELOG.next.asciidoc
	modified:   x-pack/filebeat/input/awscloudwatch/processor.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   x-pack/filebeat/input/awscloudwatch/input_test.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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