[Metricbeat] Fix cloudwatch metricset missing tags collection

[kaiyan-sheng]

What does this PR do?

This PR is to fix cloudwatch metricset from missing tags when tags.resource_type_filter is given. When user tries to collect daily storage metrics and s3 bucket tags with the cloudwatch metricset, it will fail to collect tags. This is because for CloudWatch metrics from S3 buckets, they always have StorageType as dimension. Dimension and S3 bucket name are combined to be the identifierValue in cloudwatch metricset code. But when collecting tags, dimension StorageType is not collected. That's why there is a mismatch between identifierValue and resourceTagMap.

Why is it important?

This PR will fix tags collection for all namespaces that always have a dimension reported in CloudWatch metrics.

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.

How to test this PR locally

1. Make sure the AWS account you use for testing has S3 buckets with tags.
2. Use config below for aws.yml:

- module: aws
  period: 86400s
  metricsets:
    - cloudwatch
  metrics:
    - namespace: AWS/S3
      tags.resource_type_filter: s3

3. After starting Metricbeat, you should see tags collected from S3 buckets.

Related issues

• Closes [Metricbeat] Cloudwatch metricset does not collect S3 tags correctly #17419

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[ChrsMark]

Thank you for fixing this!

Overall looks good, left some minors.