BFD-4554: Cleanup of root.tofu.tf for platform and services

[jonathan-cantu-icf]

JIRA Ticket:
BFD-4554

What Does This PR Do?

As the ticket states, to tidy up the root.tofu.tf files for both platform and services given the tflint output (i.e. warnings).

What Should Reviewers Watch For?

I actually ran a tofu plan for a couple of the modules beneath services and platform to make sure that the changes to the root.tofu.tf were not detrimental.

If you're reviewing this PR, please check for these things in particular:
That you don't see anything that could break which I may have missed to state the obvious.

What Security Implications Does This PR Have?

None that I am aware of - purely ci-cd build related.

Please indicate if this PR does any of the following:
NO to all of the questions below.

• Adds any new software dependencies

• Modifies any security controls

• Adds new transmission or storage of data

• Any other changes that could possibly affect security?

• I have considered the above security implications as it relates to this PR. (If one or more of the above apply, it cannot be merged without the ISSO or team security engineer's (@sb-benohe) approval.)

• I have created tests to sufficiently ensure the reliability of my code, if applicable. If this is a modification to an existing piece of code, I have audited the associated tests to ensure everything works as expected.

Validation

Have you fully verified and tested these changes? Is the acceptance criteria met? Please provide reproducible testing instructions, code snippets, or screenshots as applicable. To the degree I am aware of, yes, I have verified and tested these changes. I believe the AC has been met.

Try running tofu plan and tofu apply and verify there aren't any errors.

[mjburling]

I think the secondary_region variable is still necessary today, especially for cross-region configuration as seen in the KMS key definitions. For now, they should be maintained.

@malessi reminded me about one of the killer features in AWS provider for terraform v6 and above, is the introduction of a top-level region parameter at the resource level: hashicorp.github.io/terraform-provider-aws/enhanced-region-support/

I believe that may obviate the need for multiple providers and the variables that define the region in them. Again, not here, but... someday!