CMDCT-4184 sls-side prepping serverless to retain Cloudfront Distribution when removed

[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)

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

[codeclimate]

Code Climate has analyzed commit 8966ff4 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (90% is the threshold).

This pull request will bring the total coverage in the repository to 82.3% (0.0% change).

View more on Code Climate.

[JonHolman]

All of this except for modifying the CloudFront distribution can be done immediately. How about we do it now, so that we can get it over with?

[peoplespete]

All of this except for modifying the CloudFront distribution can be done immediately. How about we do it now, so that we can get it over with?

We decided to leave it here for now since all of the retains would need to be conditional if we merge it soon and rather than add that complexity and since we can't entirely get rid of pete-sls bc of CloudfrontDistribution changes, we'll keep it in the PR and then pete-sls.