Bryce/update aws onboarding

[buraizu]

What does this PR do?

Update AWS onboarding guides to reflect the new integration tile.

Motivation

DOCS-3896

Preview

CloudFormation: https://docs-staging.datadoghq.com/bryce/update-aws-onboarding/getting_started/integrations/aws/ Manual: https://docs-staging.datadoghq.com/bryce/update-aws-onboarding/integrations/guide/aws-manual-setup/?tab=roledelegation

Additional Notes

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Reviewer checklist

• [ ] Review the changed files.
• [ ] Review the URLs listed in the Preview section.
• [ ] Check images for PII
• [ ] Review any mentions of "Contact Datadog support" for internal support documentation.

[github-actions[bot]]

Preview links (active after the build_preview check completes)

New or renamed files

Modified Files

• https://docs-staging.datadoghq.com/bryce/update-aws-onboarding/getting_started/integrations/aws
• https://docs-staging.datadoghq.com/bryce/update-aws-onboarding/integrations/guide/aws-manual-setup

[buraizu]

Note: Labeling with Do Not Merge until release is approved by PM

[buraizu]

@kayayarai thanks for your review, I've applied most of your suggestions and gave some additional context on others.

[buraizu]

@warrierr thanks for pointing out those issues, updated.