d/aws_redshift_service_account: Document future deprecation

[ewbankkit]

Description

Documents the future deprecation of the aws_redshift_service_account data source and recommended replacement functionality.

Relations

Relates #27874.
Relates #29346.

[github-actions]

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[jar-b]

LGTM

[justinretzolk]

I left a couple of minor stylistic suggestions, but they're more personal preference than anything. Looks good to me either way 🚀

[github-actions]

This functionality has been released in v4.55.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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