fix: Correct loop extraction logic for tls.issuer_cert_authority

[crashGoBoom]

Description

This removes an unnecessary for_each and dynamic setting for issuer_cert_authority which is a required setting when using tls.

Motivation and Context

This fixes a bug:

Error: Unsupported attribute
on .terraform/modules/web_ecs_service/modules/service/main.tf line 257, in resource "aws_ecs_service" "this":
                  aws_pca_authority_arn = issuer_cert_authority.value.aws_pca_authority_arn
issuer_cert_authority.value is "arn:aws:acm-pca:us-east-2:SNIP:certificate-authority/SNIP"
Can't access attributes on a primitive-typed value (string).

Breaking Changes

No breaking changes.

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[bryantbiggs]

thank you

[antonbabenko]

This PR is included in version 6.2.1 🎉

[github-actions]

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