CMDCT-4184 cdk-side prepping cdk to import

[peoplespete]

Description

This change is not to be deployed until we are ready to convert to cdk. For full details of the order of events recommended to preserve our Cloudfront Distribution check out this readme: https://github.com/Enterprise-CMCS/macpro-mdct-seds/blob/cmdct-4184-cdk/import_instructions.md
The idea is that by preserving Cloudfront Distribution we will be able to deploy cdk without requiring any external DNS changes. 🎉

Related ticket

CMDCT-4184

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How to test

If you want to you can do the following to test this PR:

1. checkout pete-sls (matching master at the moment) branch
2. deploy serverless via run script (check that cloudfront distribution points at app front end)
3. checkout cmdct-4184-sls
4. deploy serverless via run script (check that cloudfront distribution is stripped down and no longer points at app front end)
5. destroy serverless assets via ./run destroy command
6. verify that distribution still exists
7. checkout cmdct-4184-cdk and comment out all code for the distribution (and things that depend on it)
8. deploy cdk via run command
9. comment IN the simplified distribution section
10. run cdk import
11. deploy cdk via run command
12. comment OUT the simplified distribution section and comment IN the final distribution section
13. deploy cdk via run command
14. verify that the cloudfront distribution is now in the cdk stack and points to the application.

Notes

NA

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Pre-review checklist

• I have added thorough tests, if necessary
• I have updated relevant documentation, if necessary
• I have performed a self-review of my code
• I have manually tested this PR in the deployed cloud environment

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Pre-merge checklist

Review

• Design: This work has been reviewed and approved by design, if necessary
• Product: This work has been reviewed and approved by product owner, if necessary

Security

If either of the following are true, notify the team's ISSO (Information System Security Officer).

• These changes are significant enough to require an update to the SIA.
• These changes are significant enough to require a penetration test.

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convert to a different template: test → val | val → prod

[benmartin-coforma]

I don't see any new red flags compared to what we reviewed before the rebase 👍