Cherry-pick #23045 to 7.x: Fix aws s3 overview dashboard

[kaiyan-sheng]

Cherry-pick of PR #23045 to 7.x branch. Original message:

What does this PR do?

This PR is to fix AWS S3 overview dashboard and also improve documentation for both s3_daily_storage and s3_request metricset.

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

• Closes Metricbeat AWS module S3 bucket misinformation #22582

Screenshots

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Build stats

• Build Cause: Pull request #23128 updated

• Start Time: 2020-12-14T23:39:41.721+0000

• Duration: 46 min 52 sec

Test stats 🧪

Test	Results
Failed	0
Passed	637
Skipped	70
Total	707

Steps errors

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Terraform Apply on x-pack/metricbeat/module/aws

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Terraform Apply on x-pack/metricbeat/module/aws

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Test stats 🧪

Test	Results
Failed	0
Passed	637
Skipped	70
Total	707